I don't know if you can reschedule, but March can still have some nasty cold weather. Of course, this weekend it looks to be in the low seventies and rain free in the Hill Country :clap I'm gone! So anyway, April is really better. That is when all the Blue Bonnets are blooming in full force as well as many other wildflowers. Yeah I know, you're not coming to see pretty flowers, but it's all part of the experience.
Regarding the quality of the roads, there are two separate issues: pavement quality and fun factor. In general, the pavement quality leaves a little to be desired. It consists mostly of large gravel embedded in an oil base. You will get good traction but it will eat your tires. If you are not used to the feel it generates on the front end, it makes it hard to guage your traction. Also, as someone mentioned, many of the low water crossings are getting bridges installed and there is some construction. However, unless it is actually raining, it should not be a problem.
Now for the fun factor. The best roads are FM's 470, 337, 336, and 335. The best Hwys are 16, 55, and 39. There are other good roads, but those are the ones most people hit. Many of them run through open range areas. Take this serious. Coming over a hill on full boil and seeing ten or fifteen BIG cattle standing in the road is not fun!! Cowpies are slick as snot if fresh, avoid them!! Also, watch for the cattle guards in the corners. They seem to always be right at the apex where you want to be at full lean. If wet, they are very slick! If you are out on a weekend, then expect more traffic and more LEO. People die out here on a regular basis from motorcycle accidents. The locals are bad about straddling the double yellows and being in your lane when they come around corners.
FM's 335, 336, and 337 are the roads for the tight twisties. FM 335 is like a roller coaster when you do the North half. Watch for rocks in the roads. They fall from the cliffs along the road. There are quite a few decreasing radius corners, off camber corners, blind corners, etc... Also, if you leave the road, there will seldom be any kind of run off other than a rock face, lots of rocks in a field, or a drop off. If you see a 10mph sign, believe it! Sliding on that rough pavement won't be fun either as it will eat right through gear. You can have a blast out here, just remember that you will be FAR from emergency help if something does happen.
Here are a few links with videos:
For FM 335: http://www.twtex.com/viewtopic.php?t=547
For FM 336: http://www.twtex.com/viewtopic.php?t=548
For FM 337: http://www.twtex.com/viewtopic.php?t=538
There are some others in there. Look for posts authored by Buck000.
Kerrville makes a good place to base out of if you are going to be riding for several days. There are lots of hotels and you are right on the edge of the good riding. There are also cabins near Vanderpool that are nice: Foxfire Cabins. I think you can find them doing a search. They have two room cabins cheap, also they have a huge farmhouse that can sleep 16 people pretty cheap. I have stayed there and it is nice. Just North of the cabins on FM 187 is the Lonestar Motorcycle Museum. It's worth a stop. They also have a dyno if you want to do some dyno runs for fun!
On FM 470 in the teeny tiny town of Tarpley, you need to stop at Mac & Ernies Eatery. It is a little yellow shack in the parking lot of the local general store. It looks like a dive, but the food is to die for! People come from all over the state and even from out of state to eat there. You won't be dissapointed. They have a website and it will show up if you search google. They are only open Friday evenings, Saturday and Sunday. Also, Wednesday for lunch only.
Another good place to eat is in Medina at the Love Creek Orchards Cedar Mill & Cafe
on Hwy 16 at FM 337. If you like Apple pie, struddle, anything... this is the place. They also have decent food. They close early though, 3:00pm!!
There are some fun roads West and South of the DFW metromess as well. If you are riding down, you might hit some of them to stay off the slabs. FM 4
down just West of Mineral Wells, then Hwy 16 all the way to Kerrville. Any of the FM's that are South of Stephenville are fun. They consist of really fast sweepers, nothing real tight. Stop in Llano at Hwy 29 & 16 for BBQ at Coopers Old Time BBQ
Well, that is all I can think of off the top of my head for now. If I recall anything else I'll post up here. Have fun!