ok , 11 days will be tight but I hope it will be a good introduction trip convincing for more later

I would suggest the following plan (I know all plans will fail but take it as idea then ):

Yangoon - arrival day and Day 1 (I guess you will also have several hours or more on your departure day) - that should be enough to see pretty everything. Try to fly to Mandalay in the evening of day 1. Train is ok also (but see my earlier notes about it scomfort) as it leaves at about 4pm.

Mandalay - 2.5 - 3 days (day 2 for the city and close suburbs, days 3 and 4 for outside trips).
Try to fly to Bagan in the afternoon/evening of day 4. If you won't fly then you will have to take whole day boat trip (day 5) which is not bad but too time consuming for your short visit (forget bus or train as those are tiring and you won't see anything during whole day journey).

Bagan - 3 days (Days 5, 6, 7) I am strongly disagree with idea of one-day flying visit and speedy sighseeing especially without sunset/sunrise experience -you will miss a lot as midday sun makes picture and viewing of temples much pale and you will be tired under hot sun.
I think you will figure out yourselves after 2 days if you want to stay more in Bagan, or you will visit Mount Popa (I did not go there but I am not saying it is not worth it) or will head to Inlay lake on day 3. We bought air-tickets in Bagan 1 day before flight (and it was busy New Year season) so I think it will be easy to decide and move on easily.

Inlay Lake - 2-4 days (depending if you want to relax a bit after busy previous days and if you want to do a day trek up to the hills). Allow 2 full days to tour the lake, villages and monastires.

This will take you to day 10-11 and your flight back to Yangoon.

2 main things to make things happenned and seen:
1) plan early start every day (say 6-7am for normal sighseeing) and 4-5am for sunrise (must in Bagan and on Inlay lake, please dont miss it). This will also allow time for some rest and long launch during hot afternoon hours, afterwards you can see things till sunset. Not much of nightlife but there are few bars where you will be ok with drinks if you want it (but pretty everything else shuts down as the sun goes down).
2) take it easy and respect local way of life (sometimes service is slow but it is just their life and many myanmar people don't know that travellers expect it speedy, like in western world or in HK/SG). but absolutely majority of people made a real effort to make us happy, and they well succedded^

As for the money, I think you can find current airfares on websites of Air Mandalay and Air Bagan (sorry I dont remember but I think they were about $50-70 per flight in Dec 2005, can be higher now with oil price hike last year).
Daily costs, well it depends on your taste and habbits but we paid about:
12-20 US$ for clean double-bed rooms (with hotwater and aircon but nothing funcy, but we ok with those to sleep in and take showers only),
guides cost ~10 US$/day (incl horsecart or longtail boat),
food and drinks - say 1US$ per single meal (mind you, we enjoyed street food and not those tourist restaurants ) or beer.
If my memory still works, we had exchanged about 800 US$ into local kyats on day 1 and it was enough for 2.5 weeks of travelling includinig all internal flights, my beers and her bit of shopping

ok, i guess you are tired reading this so you better go there and check yourselves:-) enjoy, I hope you will ^

mishkira