We bought one late last year, the 17B model with the queen bed up front.
So far we have:
-- added a 3" memory foam topper to the queen bed (making the bed it came with sort of a box spring, which it is far better as than it was a bed).
-- cut the dinette table back about 2" to make it easier to slide in and out of. We kept the piece we cut so that when the table is folded down we still have the full length.
-- added a second battery up front (that took angle iron and welding)
-- disconnected the %$#^ radio. I'd like to find a smaller microwave, remove the radio and top-mount the microwave and get the space the mwave currently sits in for more drawers/storage.
-- built a cover for the stove to make that space more useful - unless it is VERY cold (like sub 20s), I prefer to cook outside, and I'd like that space for something else.
-- added a paper towel rack above the sink
-- added a "keys and wallet" shelf mounted to the wall below the stove on the left (as you look at the stove).
-- added a soap and TP wire basket tower to the bathroom (like this one, although I can't remember where I actually bought the one we have
Amazon.com: InterDesign Rain Tension Caddy, Clear: Home & Garden
-- built window coverings (out of car windshield sunshield materials) that cover the 3 windows in the back of the trailer. If you are camping in the high country, those single-pane windows let in a LOT of cold. I thought about insulated shades, but those are expensive and this was much easier.
We just picked up some alder to build a few more cabinets (we've been experimenting with stains to try and get as close as possible to the factory colors). One will run along the back wall of the trailer, above the window (we have no interest at all in the TV mount). Other cabinets will be above the queen bed, although we haven't decided on design. Newer trailers have a cabinet very similar to the one above the stove that runs the same direction as the axle above the bed. I was thinking more of two cabinets, one at the foot of the bed and then a shelf above the head of the bed.
Ours is a slightly older style and we don't have the pass-through exterior storage under the front bed - as soon as the warranty is out, that gets installed.
After camping a couple of times with the "bag" style awning, we're looking for a different awning - because of the relatively small distance between the door and the awning rail, most after-market version won't fit. I believe the one FR uses is an AE 9000, but I'm currently talking to Chris in FR Cherokee customer service to verify the model number. If it IS the AE, it's around $750. The biggest problem with retrofitting the awning is that there may or may not be suitable frame members to mount to at the base. Fortunately, that area is below the dinette seat in the read and below the bed in the front, so if we have to cut through the flooring to add bracing we can without making a real mess.
Other notes:
we tow with a 2004 V8 Jeep Grand Cherokee. Even though the rated tow weight is almost twice what our trailer weighs (verified on the scales, our trailer, fully loaded with all of our camping junk, is about 3300 lbs), it tows much much better with a load level hitch and an anti-sway. The Jeep gets about 16/20 alone and about 13/16 with the trailer.