I would bring several lights in a couple of catagories.
1) Bright light for those things that go bump in the night, signaling and searching. Two lights come to mind, the SF M2 w/LOLA or the UK 2L (or 4AA). The M2 is very rugged and has a nice beam. The 2L is cheaper, also rugged, longer runtime, mega waterproof but it has a so-so beam and is a twist-on. Since you (original poster) asked for a light for things that go bump in the night, I figure the twist on might be less optimal. In either case I would bring a spare LA and some spare batteries. I would bring a SF V72 holster for the M2.
2) Task/utility light - the main light you grab when you need to do something in the dark. I could see this either as:
Something about 3 LEDs and AA batteries. Preferably regulated. I think the AA Minimag w/Newbeam, glass lens and Kroll tailcap are good, but there are other good options out there.
-or-
Regulated LS. My choice would be a AA Minimag with Badboy 400mA, glass lens and Kroll tailcap.
I think I would lean towards the Newbeam because you can adapt to the light level and the extended runtime would be a big advantage if things went wrong and you needed light over a long period of time.
[ Note, The SF L1 would probably be a good replacement for this selection once it comes out since you get both the low and "medium" brightnesses from the same light ]
Remember batteries and consider a Jackstrap or Niteze headband. A holster would be a good idea.
3) Headlamp. Something LED based, waterproof, AA based, 3 LEDs would be good, something that more LEDs but could select between the number would be better. Best would be the HDS Actionlight, but you can't actually *get* them so that's probably out.
4) Backup light. CMG Infinity or CMG Infinity Ultra. Ultra long runtime, small, bulletproof light. Runs AA batteries. Personally, I'd probably use the Ultra and bring an extra battery or two.
5) Bonus light. Arc AAA. Small, rugged. While it isn't as necissary as the above lights, I just can't help myself from having the Arc. In a lot of ways I use this as a compliment to the Ultra. I typically load the Ultra with lithium batteries and leave it stowed. The Arc takes on a lot of utility duties and the Ultra is always charged in case of emergencies. The downside is the AAA batteries are a bit heavy for how much light you get since I normally use lithium cells. This means I typically only take about one spare for the Arc.
6) I typically use lithium batteries when I pack so they are lighter and work well in cold weather.
7) Don't count on a light for Bears. Maybe some OC spray, but mostly read up on them and use your noggin.
(I'm assuming you have the other gear covered already.)
Be safe,
-john