Regardless of brand, power level, or price, you will definitely be happier with a tube amp than a solid state. Tube amps usually cost a bit more, but you get more sound per watt than with a solid circuit. The sound of a tube amp is simply warmer and more full, and your guitar will sound more musical and less artificial.
You'll probably pay around $400 - $500 for an entry-price all-tube amp (new), and brands like Bugera and Peavey make decent tube amps in the lower price ranges. If that's too steep, the next best thing is probably a VOX ValveTronix which has a single tube in the pre-amp section. A VT20+ can be bought for about $250 new, and they have some decent effects built also.
ACOUSTICS: Cordoba D10-CE / LaPatrie "Concert" / Takamine GD30CE-12 / Norman ST30
ELECTRICS: EP Les Paul Custom Pro / Gretsch Streamliner G2420T / Cort GB34 Bass
AMPS: Traynor YCS50 / Peavey VK212 / Traynor AM150T / Fender Rumble 150
EFFECTS: Boss ME-80 Multi-effects / Ibanez WD7 wah