Trail Ridge isin't opened yet, and the park lakes are allmost 100% still capped.
There are Crappie in Estes lake. They are rare, and you have to know where to look.
Estes lake is fishing really well. I'd recommend fishing a fly/bubble set up.
Typical Trout lures (Thomas Boyant, Tasmanian Devil, Panther Martins, Super Dupers, etc..) usually work.
The lake is for the most part very shallow. So I'd look for an area to fish that drops off. Waders (or tube or kayak) would help.
Marys lake in Estes usually fishes good in the spring, but I haven't heard from anyones whos fished it recently..
As for the river, I would always check Kirk's Fly shop's weekly report. Here's a link to their recent report. (including flies to try on Estes or Marys) [log in for link]
Good luck, and post a report with pictures when you get back