In my opinion packing in makes gear selection a little more critical. If you don't already have the gear it can add up quick. If you already have a pack you like that's good. Hopefully you can pack in with it and then compress it down for use as a day pack to hunt out of. As far as other gear I would say some things are more important then others when it comes to spending money and getting ready for your first trip. Of course if money is not an issue you can go crazy. For example binoculars or spotting scope. This is your first hunt. Are you going to pass any legal animal? I would not suggest it. If your glass is good enough to see that those are elk on the other side of the drainage does it matter if that's a 5x5 or a 6x6?
Besides your bow and hunting gear I think the three most important things to consider are
1. Boots. Think hiking, not hunting. Water proof and broken in.
2. Clothes. Since your packing in you don't get alot. No cotton. Layers to keep you comfortable from freezing to 80 degrees.
3. Rain Gear. The best you can afford that will hold up to the hunt but is still packable. Obviously you want it quiet. I like something that can work as my outer layer when it's cold and windy.
You can also learn alot from the western forum of Archery Talk.
I also like.
http://www.rokslide.com/
http://www.elknutforums.com/Hunting/
And if you watch this site you can find some really good deals.
http://www.camofire.com/
To this I will add always be ready. Stop for a break keep your bow handy. Your opportunities are few and far between. Be ready to make the most of them. You have to like to hunt as much as you like to kill.
Oh yeah. Get a good head lamp and like hiking in the dark!
ANd know your GPS
and I could go on and on......