Here is what you want:
Fender Champion
http://www.zzounds.com/item--FEN2330100000
Epiphone Valve Junior
http://www.zzounds.com/item--EPIEPABKJR
Give those little guys a shot. They're light weight, plenty loud, and you can get some great tones out of them. The volume knob on the Champion is very dynamic, and you can get some great sounding stuff at many different volumes. They're plenty loud for playing with a blues or classic rock band (especially if you're micced). Plus, they're pretty cheap, so it's not like you're making a huge investment.
And if those aren't loud enough, get a Tweed Blues Jr. or a VOX AC15. I live in an apartment, and it's possible to turn down the Blues Jr. enough to play without bothering anyone, and still get some nice tones.