The "thin" sound is prob due to the small speaker in the Vox. Look for something with reverb and a 10" or 12" speaker.
Just about anything solid state should work fine for clean. Peavey, Roland Cube, Fender Frontman. Should be able to pick something up for $200 or less. Other than reverb, I'd go for a compressor(on a light setting) for some jangly sustain.
My fav rig is my Orange Micro Terror head and a 12" speaker cab. $149 for the head, $100 for the used cab, and a reverb pedal somebody gave me. Even tho Orange is known for distortion, it sounds great clean. I even did an acoustic gig with it. (LR Baggs M1A soundhole pickup). The orange is super simple to grok. Gain, volume, tone.
Another great little amp is my USA Crate Vintage Club. 10" speaker, reverb, all tube. Again, dead simple to operate. I sometimes see these for $150-$200 on craigslist. The Crate Palomino is a later version of the same thing but made in China.