Lucky you indeed! I lived in Glenwood Springs for two years prior two moving to WA. I fished the Frying Pan all winter long, and it is all it has been said to be in the other posts here. Use mysis for the hogs up to 12 lbs or so in the first 500 yrds below the dam. Expect company in this streach, you may be shoulder to shoulder with the trophy hunter subculture in the toilet bowl and bend pool. These fish are caught and released a lot and start to act like trained seals. Plenty of good fish downstream, nice water and still some astonishingly big rainbows that seem to migrate downstream and back. This time of year you will do well with midge larva, black and red. WD40 and black beauties will catch lots of fish (small, 18-24). Pheasant tails are also clutch, I used to tie them black and these outfished brown for me. Again go small, 18-20! This water is often gin clear so 6x fluorocarbon or 7x mono, and keep casting, some days they wont move out of their feeding lanes. The canyon is spectacular, but much of it above 8,000' so bring your neoprene, dress warm and expect snow.
The Roaring fork is also world class, but a freestone, so depending on water levels could also be great. It flows from Aspen to Glenwood. Prince nymphs, midges, and despite what you are told, stoneflies will tie you into some nice bows and browns that don't take kindly to being hooked. Best of luck to you!