a 2-3wt is what I use for high lakes. Mine's a 6'6" 2pc. 2wt. I mostly use it for streams, but it holds it's own on lakes. My ideal backpacking rod would probably be a 7-7.5' fiberglass 3pc. 3wt. Not really light, but they're fun!
I built myself a 7pc 8' 3/4wt. Packs down to almost nothing. Medium action that roll casts well. Can shoot decent line from tree lined shores with a steeple cast. No sense not carrying it and a small fly box along.
I've packed in to many a lake and the last thing I want to do is to hold a long rod tube in my hands, especially when pushing through brush. Shorter rods tubes that can fit in a pack and leave one's hands free for trekking poles are a better solution.
But a 9' rod, even in 4 pieces, still leaves a sizeable length of tube poking out of the top of my packs to snag brush and low hanging limbs or to get hung up while squirming under fallen logs. I prefer shorter rods in more than 4 pieces that fit into a tube that will fit entirely inside my pack.
Weather is more variable at higher altitude, so sudden gusts can play games with light lines. As a result I've moved away from 2wt and even 3wt rods and favor 4wts, whose heavier lines seem more immune to wind gusts.
I'm having a 7'6" 6-piece 4wt Lamiglas fiberglass blank built out right now. I enjoy the slower action and the short (~15") tube will easily fit inside even a small day pack.
I used to use a Fenwick fiberglass 7 1/2' 6 wt 4 pc. Then I graduated to my Sage 9' 5 wt 2 pc, and I put a rubber cap on the bottom of the rod tube to use it as a walking stick, but it's not handy for bushwhacking. Subsequently I made an 8' 5 wt 4 pc that packs small and light. I also have an Ordella 9' 5 wt 4 pc that I haven't backpacked with, but have used on Alaskan bush trips. I like the rod and might carry it in my backpack; it's only 3 inches longer than the 8' rod.
I've never had a rod less than a 5 wt. 3s and 4s seem popular, but I'm not sure why I'd want one. Seems like any amount of wind would put most casters out of business.
I have done it many ways. I used to use a 9' 6wt 2pc. with a custom ABS tube which doubled as a walking stick, balance pole for crossing logs over streams, and a "never needed" weapon. In recent years I took 6'6" 3pc 4wt until I fell and broke it. Then I went to a Fenwick fiberglass 7' 4pc 6wt. Short light rods are great for small flies and calm days. Some of those lakes have big fish, windy days, and a need to roll cast. In the end it is a personal choice like all of fishing and there is no wrong or right configuration. Just remember to think roll casts and wind when you make your decision.
I've been using two rods for this lovely chore. My first choice is a 8.5ft,5wt,4pc. Marryat Packer. Marryat made a small tube to pack this rod in and it works wonderfully with most day or day+ packs. The action is on the slow side of medium fast very similiar to a Winston LT. My second choice is a Sage SLT in 9ft, 5pc.,5wt, slighty faster action than the Marryat but it travels in a shorter package. I take the Sage on my longer trips.
Two winters ago I built up a 5wt. 9' 7pc. rainshadow blank. It is a medium action but with the 5 wt. line it still works well in the wind. It fits in a 22" tube that can go inside my pack and not have to be strapped on the outside. I've only got to use it twice because the weather last year wasn't the greatest for high lake camping. I'm to old for snow camps. Before that I used a 2pc 9' in an aluminum tube with a rubber cap on the bottom for a hiking stick. Once I tried a pair of "real" hiking poles I bought the 7pc. What a difference.
About ten years ago, I built myself a birthday present: A Scott G series 8'4" 5-piece 4-weight. Nice TiCh guides, silk wraps, and a sliding band reelseat.
It's the alpine lake rod I'd wanted for many years, working up from a horrible 6-section Wright & McGill, through various multi-section glass, telescoping tubular glass, and graphite. But as airlines became more restrictive in their luggage requirements, I found that it's easier to carry the Scott in a backpack as carry-on luggage: trout from here to Colorado to Virginia.
Whether they are ideal or not, this is what I use:
Redington Wayfarer 5-pc, 7'6" 4-wt
Redington Wayfarer 6-pc, 9'0" 4-wt
Both pack down to a little over 18" and fit inside a pack, instead of sticking out. As Kent mentioned, nothing is more annoying to be bending under a downed tree or low branch with a heavy pack only to have your rod tube hang up.
They discontinued the Wayfarer, but I like how they cast and they were not expensive. You might still be able to find some of them available, if you look around.
I have a 5wt 8'6" I think 5 piece Rainshadow a friend built for me. Works great. A good lightweight tube option is to go to a FF shop and see if they have any of the clear plastic tubes some rods come in-they might sell you one for a couple of bucks. Then you cut it down to the right size for your packrod. I bought mine at the excellent McCoy's Tackle Shop in Stanley, ID. Another tip for high lake fishing where light weight is important: make or buy yourself a lanyard/necklace thing for your tools. I made mine from a lanyard like they give you at a convention from stuff I had around the house.