I would stick with a 9ft rod. For distance you need to learn to double-haul. If you can do that then a shooting head system rated a couple of sizes higher than the rod rating will get you out there (e.g. on a 6wt rod go with an 8wt head). Sinking heads are easier to launch than floating because there is more weight concentrated into a slimmer profile and less wind resistance. On a fast sinking line you can get away with a short leader. 3 feet of straight mono will be fine.
If fish are feeding near the surface then go with a floating head. Shooting heads are great for distance but the presentation will be eratic. If the fish are deep that won't matter but if you're casting to rising fish taking midge or sedge pupae you'll be better of with a WF line.
You'll lose a bit of range but the presentation will be a lot better. You'll also want a tapered leader of at least 12ft, preferably more. As you get more comfortable casting with this 'finesse' set up it pays to go with as long a leader as you can handle - up to 20ft. The further away your fly is from the end of the flyline the better.
Hope this helps. Back home in the UK almost all of my freshwater fishing was on reservoirs and a long cast was a huge advantage.
p.s. welcome to the forum. I see you're in Idaho? I hear they have some good trout fishing out there.