There is a thread just below titled RPU and GPU usage - it will provide you with most the answers you need and also hints on how to guide you through the GPU game

It's a gamble.

My GPU upgrades have cleared 90%+ over the last few years. I typically pay an extra $1-300 USD each way for W+, but I get a lie flat seat 90%+ ($2-4000 in value) of the time. So it is a good deal compared to buying business, or using miles + copay.

If you are looking at the bottom line, and don't consider business to be worth hundreds of dollars more on a long flight, you have to do a lot more work.

1) Look for mid-week, off-business times with available R (use expert mode on the UA website). If you buy a W+ with R > 0, you get a 100% upgrade, so it is not a gamble.

2) Save the GPUs for trips on higher demand days, or with shorter notice, so the extra cost of W+ is not too high.

3) Use them domestically, latin america, Caribbean, Hawaii, etc. Much easier to find R > 0, you jump the CPU queue, and there is no extra cost to using them.

4) If your GPU doesn't clear by T-24, look for a SDC (same day change) with either more unsold business (J/C/D/Z/P) or available R (often found within T-24). Changing to these flights will get you an upgrade (may need to call to cut the line when R > 0, see other threads) or increase your chances.

Well, technically there are multiple W-based fares on many routes, and they may be priced widely. But yeah, I don't believe UA typically offers different W-based fares depending on the availability of R space--unless, of course, the reason there's R is that it's close-in (in which case a 21-day advance purchase W fare won't show up, but the more expensive 14- or 7-day AP fare will, assuming there is such a W fare in that market and IM deems it worthwhile to release it...).

I always fly with my wife (who is also a 1k) and we have a 100% success rate applying our GPUs over the past few years. We only use them to secure lie-flat seats on TPAC and TATL flights.

I have found the spread between the lowest and W fare to be between $100 and $800 with the TPAC spread larger than the TATL spread.

I have always waited until I was able to find R > 2 space before booking. Now I usually need to search multiple routings and be flexible with scheduling in order to find free R inventory. For example if we're flying to Asia, I check EWR/ORD/DEN/SFO/IAH (etc.) - NRT/ICN/HKG (etc.) looking for R space. If we're flying to Europe, I'm checking EWR/IAD/ORD - LHR/FRA/BRU/MUC etc.

But so far at least, it has worked for us.

What others have said is valid but it is certainly getting harder every year to burn the GPU's.

This is exactly my experience, and my method for using GPUs. All my business travel is domestic however, so my personal international travel affords me more flexibility in booking with GPUs. I'd probably be very frustrated if trying to use them for business travel when schedule trumps everything.

It is getting harder to burn GPUs. I have two left this year and may struggle to use before end of Jan 2015. It's hard to balance the cadence of usage too - you want to use them wisely but not get left with spares! I've missed 3 applications of GPU in the past month:
1. SFO - JFK p.s. (booked and applied GPUs for me and companion 3 weeks out with no R space but 10 biz seats open) 1st on list -24, 1 seat open, but no dice, lost to 'buy up' I guess.
2. EWR - NRT on W (booked and applied GPU for me 2 weeks out, no R space but 12 biz seats open) -24 showing space in biz, 2 seats, 2nd on list then lost out to a 'buy up' again I guess.
3. EWR - CDG sponsored non-member on Y (booked and applied GPU 3 days out, no R space and only 2 biz seats open) -24 no space in biz, 1st on list but no GPU clear.

My advice is to apply GPUs liberally on long flights whether domestic or international and to not wait to use. It is getting tougher to guarantee their clearance.

As an aside I am currently doing an AAA EXP challenge - with AA if you don't clear (which happened on a recent intercontinental flight) they recognize this and treat you really well in the economy cabin - free meals, movies, personal attention, etc.

Yeah I can see how it would be frustrating trying to apply a GPU if you had to fly on a particular day. My TPAC flights are usually for business (my TATLs are usually leisure) but because my work travels with me on my computer I have +- several days to choose for departure and return.

If necessary, we enjoy hanging out in Bangkok or Seoul or Singapore for a few days, and we'd rather pay the freight for several days at Raffles or Mandarin Oriental than to United for the 14 hour full fare experience. And my wife is completely flexible with schedule.

When I'm flying TATL or TPAC it's either in paid J (for work) or on an award in J (for personal), so the "G" aspect of my GPUs doesn't help much. For my purposes they're really just more RPUs and I tend to use them for ps flights or other transcons.

My last year as a 1K was 2013 and it was so bad that I could not even clear GPUs on domestic flights. I burned 2 on a domestic flight that cleared into R at booking then had to throw away the other 2 because I could not even clear them on CPU eligible domestic flights through a waitlist. Out of the 6 GPUs I had, I was only able to use 2 for an international flight, and that was booked straight into R class that was open at booking. So, for OP, don't waste your time on this rigged game of hoping they will let you upgrade later. Find a flight with R space, and book into that. Paying for W then upgrading into R is a good value. Paying for W then sitting in Y then throwing away unused GPUs is awful.

I use my GPUs as RPUs on domestic flights. Mostly as gifts to friends and family, and sometimes for myself on the occasional TCON.

As others have noted, booking flexibility and same-day changes are the key to success in using GPUs effectively.

Note that the W fare bucket or up only applies to intercontinental flights, not North America or Hawaii. Also note that Q and V buckets can actually price lower (in the $100 range) than W on some TPAC or TATL routings. I always search for Q,V,W fare buckets to see which provides the lowest fare .

My preferred approach is to book one-way itineraries (where there isn't a price premium) to insulate same-day changes from messing up down-stream flight segments.

I use them to confirm BF for MsHalls120 and I at time of purchase when going on TATL vacations. That burns 4, and the rest I use on business trips.

Actually, there are several posts/threads re: GPUs.

Me too as I never fly international, at least on revenue. So I apply to my domestic flights if I see I am way down on the list (very rare) or give to friends and family. Just recently surprised my dear old friends by applying my GPUs to their short flight from MSY to IAH It was a bigger RJ and they loved it!