#1 Gold doesn't give a huge amount in the sense of upgrades, discounts etc. What is does "aim" to give you is a smoother rental experience - e.g. less paperwork, less hassle at the rental station. I've found this very useful as it makes things an awful lot quicker at times. One tip I have is that it's worth enabling your profile (by completing car/insurance preferences etc) for all regions when you first sign up - I'd forgotten to do Australia prior to a trip there earlier this year, and as a result had more paperwork than I'm used to.

Re differing prices - are they quoting you like for like rates? It may be the case that without logging in, you're being quoted pre-paid rates, whereas #1 Gold might be quoting non-pre-paid. Usually there's an option on the quote screen to switch from one to the other (and vice versa).

It's also worth adding all of your CDP#'s (discount codes provided by a variety of sources - e.g. Amex, BA, PriorityClub, COSTCO, various others) to your #1 Gold profile. That way it will automatically quote including any discounts you're entitled to (although it will quote your "preferred" scheme first - but you can switch between CDP#s quite easily).

Hope this helps!