Heed the wisdom of Glenn. Glenn is the grand old man of the sea as far as hiking in the southwest is concerned. When he speaks - one would do well to listen. Wisdom through many years of experience.
Matt also gave you some good comparative info.
Personal preference and comfort play a role as well. Frequency of use is another factor to consider. If you only do the occasional overhighter - then maybe the cheaper route of synthetic is the way to go. If you are a more avid backpacker and you are concerned about wight/durability/size - then go with down.
Whatever you decide - when you go to the store, take off your shoes and climb in the bag, then roll around like you're sleeping. Try that bad boy out. Don't just buy it cause it looks cool or somebody recommended it. I know a lot of people that loved the old NF Blue Kazoo. I hated it - too constricting for my big frame (6'4" 220 lbs. - all muscle of course
). I need a bigger bag, so the smaller mummy bags just sucked for me. Even the long versions rarely did the job.
Select a few criteria for yourself, weigh your needs and prioritize the cirteria accordingly, then make a judgement call from there. Some criteria to consider:
- - How often will I use it?
- In what type of weather will I use it?
- What will be the temperature range in which it will be used? (take the extremes from both ends - and strongly consider the most common tempreatures)
- How important is comfort?
- How important is durability?
- How important is weight?
- How important is size?
Once you have answers to all those questions, you can look at the specifics for various types of bags and come to a pretty good decision on which bag is right for your needs. Then go to a store and try a few out.
My personal recommendation for a store to try them out is REI (you can get a lot of specs on the sleeping bags online here
) - they will most definitely let you try them out.
'Weird is a relative, not an absolute.' - A. Einstein