Several parks here on my list, so here goes!
Dollywood:
Wow I could go on all day about Dollywood! I'd say start off by each year renovating one of the older rides, especially the water rides. Daredevil Falls could really use a refurbishment like Knott's Berry Farm did with Timber Mountain Log Ride. Smoky Mountain River Rampage and Slidewinder also could use a facelift.
After that, I'd put the primary focus on Timber Canyon, first off renaming it to Timber Gorge to be geographically accurate (there are no canyons in the Smoky Mountains, reference the nearby Little River Gorge). That portion of the park has always felt like it's missing something to me. I have two possible ideas for the former Timber Tower site.
First would be to install a top notch launched freefall. If it's launched you could theme it to a dynamite blast, while if it is a standard drop the theme could be a tree falling. The return of Timber Tower, just as a freefall!
The other and more interesting idea for me would be to turn the pool into a beaver habitat, with the current picnic area serving as an observation site. The current area occupied by Lil' Loggers Landing could be another observation area with educational information for the guests.
Also I think they should put a larger restaurant on that end of the park...possibly replace the pizza place, and finally I think it would be a cool idea to have a lumberjack style show there year round...I know they are debuting one for Festival of Nations this spring.
Finally it would be nice if the park would expand into the train loop area. They could fit a couple of new coasters up that way. If Dollywood just got an invert, fast launched coaster, and some form of giga/mega coaster, their coaster lineup would be perfect!
Carowinds:
Carowinds needs to replace a couple of coasters...remove Nighthawk (who wants to go through those 2 hour waits anyway to get your head banged around?) and get a nice launched B&M wing or flying coaster in there. Also Carolina Cyclone has just got to go. Last thing on my list would be to convert the Hurler to an RMC hybrid. Those little hills would make some great barrel roll elements!