Absolutely. I was silver for years, then made Gold one year due to a huge long-haul trip. The upgrade rates were so much better that I go out of my way (and spend a few extra $) to ensure I make Gold ever since.
I don't track my upgrade percentage, but unless I'm flying PHL/BOS or PHL/PHX, I typically get upgraded. Since my wife and I try to find off-peak times for vacation flights, we nearly always get upgraded together on vacation trips as well. That is definitely worth it to me... keeping her happy that is.