I have several larger packs but I'm looking for a lightweight day/overnight pack. Maybe something in the 35 to 45 range. I've looked online at several but actual reviews are limited in this pack range for some reason.

Would be using it on long day hikes in the Rocky Mountain National Park or overnighters throughout Colorado.

Anyone have any experience with this size of pack? Example would be the Gregory Z35 to Mountain Harware Fluid 48.

My long-distance backpacking pack also works great for short overnight or dayhikes; it's just not that heavy and I'm used to it.

In that context, you might consider the ULA Circuit, 2-1/4 pounds. Or perhaps even the Ohm by the same manufacturer. I've seen a lot of ULA packs on the trail and never met an unhappy owner.

The first question has to be, how much weight will you carry in this pack? It makes considerable difference if your total pack weight for 1-2 nights is 15 pounds or 30 pounds. For 15 pounds total, you would probably do fine with a lightweight frameless pack (check out Mountain Laurel Designs, ZPacks, Six Moon Designs Swift or Gossamer Gear)--most of these packs weigh a pound or less. Most people get uncomfortable using a frameless pack with a load over 20 lbs. (this varies by individual, of course). For a 30 pound load, you need a far more substantial pack with a frame, such as the ULA Circuit or Catalyst (the latter probably too big) or one of the smaller Osprey packs.

My pack (Six Moon Designs Comet, older model) works fine for either short or long trips. I just compress it more for shorter trips. The main body is 2400 cubic inches (40 L). I do stuff things like water, snacks, the tent (very compact) and rain gear in the outside pockets, but they're not full either. I've never had to use the extension collar, even for 10-day trips or backpacking with the grandkids, and I'm seriously considering cutting part of it off to get rid of the velcro closure. Unfortunately this particular pack was discontinued in 2006, or I'd recommend it as a possibility. Its cousin, the SMD Starlite, at 60L is far too big.

You really have to try on the pack and hike for several hours around the house or neighborhood with it, keeping it clean so you can return it, with all your gear (including the equivalent of your food and water) before deciding. Pack fit is almost as individual as shoe fit!

I've been playing with an Osprey Hornet 46 that I think would do pretty well. It's very light for a pack with a rudimentary frame, holds enough to easily support two-night trips and compresses effectively to perform as a spacious day pack that doesn't have the gear collecting in a big lump on the bottom. The top pocket's also removable.

GoLite Jam might be another decent choice.

Cheers,

I've got some very limited experience with an Osprey Kestrel 28 I recently got to use as a day pack; I do like it, so far. I have more experience with the Kestrel 58 and 48, which I use for weekend backpacks - I'm very enthusiastic about them. Since all 3 are essentially the same design and suspension, I'd say the Kestrel 28, 38, or 48 would work, depending upon how much weight you want to carry. (I'd estimate 25, 30, and 35 pounds, respectively, to be the comfort limits for those packs, depending on size.)

They're not the lightest out there, but I've found they have (for me) the best balance of sturdy suspension, feature set, and weight.

I use the Kelty Redwing 3100 (50.8 liters). It has an internal frame, although I'm not sure if it can be considered a full-framed pack. Great for over nighters and long day hikes. I elected for the larger pack because I like have the room to stuff a heavy jacket in it if need be. I have the '09 model (I think) which can be found online for around $65. It weighs around 3 lbs 6 ounces.

Might be a little overkill for what you're looking for, but I absolutely love it.