I don't know what kind of $$ you're looking to spend, but if fund's/storage space permit, get a nice-sized one with a kerosene burner to heat the water. You'd be surprised how much more you can do with 900psi of 200*(+) water than you can with 2000psi of cold tap water. You can even get a decent used hot-water unit for not much more than a new cold-water one. For what it sounds like you plan to do with it, a used one would be just fine. Look in your yellowpages for dealers.
Karcher and Landa are good names to look for in hot-water models. I'd personally stay away from anything with 'Jenny' on it. We had one where I used to work and it was nothing but trouble, alot of electrical glitches and mechanical failures... it was down about half the time.
Just some suggestions, good luck in your search