I don't think you said what you'll be towing with, but keep in mind the wood-deck trailers are usually steel. That weight + 3 bikes can add up. Will they only be sport-bikes?
I bought a trailer from a dealer who sells Worthington tailers(
www.worthington.com) Very nice open trailer, all aluminum and VERY light. Not that it matters, but I think it looks pretty cool too. The three chock trailer easily tows two VTX 1800's (at least 800lbs each), and I don't even feel them behind my Trooper.
They build it like you want, and I had an extra foot of floor added to mine. I'd also recommend a tongue jack (with a wheel.) If you don't get it with the trailer you can buy one at Wal-Mart or any boat store for about $60.
No damage on trips...just dust sometimes. I wouldn't cover them with anything. Like the previous post said, anything flapping at all quickly works with the wind to sand and scratch surfaces. I also would not recommend running a strap through the wheel. Even just a little movement can wear a "hot spot," no matter what you use to protect it. That's a lesson learned from a previous bike
