The key is to do what is personally satisfying and what meets your personal goals.
Differences here are mostly semantic.
Bill is right in his reference to the influence of average income and population as far as they affect available work and rates.
DNJ is right in his reference to not "rolling over" and just accepting whatever is offered in compensation.
In my area, there is tremendous pressure by "marginal" players to play my $150.00 restaurant jobs for $75.00. If a club owner dosen't know the difference between good and marginal performances, there's not much else to do but find better venue.
I LIKE upscale restaurant jobs (oops, almost said "GIGS"...sorry, UD). I've worked restaurants in the summers for over 14 years. That gives me access to people who hire entertainment for much higher paying corporate, government and other private jobs, and to the organizations that hire me for film and graphics work.
There's also an art to doing it right...the right tunes, volume, etc. I don't mind being "walpaper", because you can practice on someone else's nickel. Also,playing a wide variety of requests is rewarding (read good TIPS).
Everyone must set their paramaters and figure out how to make it work. I don't play bars, nursing homes or country music, use a tip jar or sell CD's...nothing against any of the above...it's just not for me.
The key is to be professional, always keep learning and improving and enriching lives with your abilities.
Keep the music "HAPPENING"!
The best, always,
Russ