which would likely sell for more?

I'm certainly not getting rid of my xr650r so don't worry. I currently have my xr650r (plated) and a drz400s (comes from factory with plate of course) and saw on craigslist a guy who was willing to trade his 2001 R with California plate for a smaller bike, specifically a drz400s. Both the 01r and my 02s are clean and I would say equal in terms of wear (or lack their of), cleanliness, amount of/type of riding and equally well maintained. The 01 is bone stock (as far as I can tell, he didn't make any mention of anything in the ad) and my 02s has a 3.7 gallon tank on it, wide foot pegs, rejetted, 3x3 airbox mod, installed a kickstarter on it and I think that's it. If I were to do this trade would I be making a good deal? I'm eventually going to put the drz on craigslist, but if I could get more money by trading and then putting the xr online that would be the preferred route obviously. Thanks for your opinions.

Bit risky to do as you might end up keeping two pigs  

that's my biggest fear, hahaha. I have had both the big and the drz for the past 4 months or so and have no reason to sell the drz so haven't. I don't use the drz though so I figured if I'm getting a good deal, I'll trade the drz for the xr and then if I need to sell it I will, but I don't need extra money so don't mind having a spare bike. I like the idea of having another brp in case something happens to something on my bike, then I have easily accessible spares, not that anything would go wrong with my R, but it would be comfortable knowing I have a secondary one. I would only do it if I was getting the better end of the deal though, like say I did suddenly run into some money problems and had to sell a bike, which would fetch me the most money back?

Have a look around , what is for sale and compare the prices , sorry i can not help you because i am not expert in California market , over here those two bikes are priced closely , but of course i am talking bikes in a comparable condition . I think that having a spare piggy could be great as a good source of spare parts ( it works out so much cheaper to buy whole pig now than buying the parts from honda , for example you can have whole bike for the price of a frame from honda   ) .