Again, I can't thank you enough for all your help!
I went to my local camera store today and tried out the 10-22. 10mm is quite a difference from 18! I then tried to see if they could come anywhere near B&H prices (so I could support a local place), but they wouldn't even budge a few dollars and they certainly wouldn't match the current price.
Needless to say, I went home and purchased the 10-22 for my trip. Thank you all for your wonderful advice, and for reassuring me with what I was leaning towards in the first place.
Sorry I didn't acknowledge everyone earlier.
rlaverty - thanks! I'm really looking forward to the trip.
Fat Daddy - I am definitely going to make sure the Going to the Sun Road is included on our trip. I've heard quite a bit about it.
Texphoto - It's a great idea and as much as I'd like to, I think renting another body would be a little too expensive for my taste for just one location on our trip.
Robby - I do plan on renting the extender, so thanks. I'll have to look at Polebridge.
RLP - thanks for your input on the lens
Standard - unfortunately, I am not a huge fan of the manual focus only sticker on that lens (at least not at this point... so Zeiss lenses are out too I guess...
Scrappy - I liked the 1.4 extender, as I also tried both of the extenders at the photo store. I really didn't notice much AF slow down or accuracy issues at all with either extender, so that was super nice!
Neuro - thanks. As a side note I appreciate your more technical posts, as I am an engineering student myself (I believe I remember you are some type of engineer, but I digress)
Steve - yeah that's kind of what I was thinking and seeing via flickr.
Distant - I completely agree! I've missed several pretty stellar shots because I sometimes just have to put my camera down and soak it all in.
Halfrack - I'll definitely consider renting both converters, and I'll definitely bring my trusty tripod and trigger
Alan - I looked into that after your post, and I must say it looks pretty interesting. Thanks!
Michi - That kind of surprises me, but that's awesome! Thanks for your input as well.
bholliman - I am really looking forward to the trip! Sorry to make you jealous, but hopefully you'll get to make it back soon!
Michael - I will definitely bring a CP with me, as well as a ND. Thanks for your advice on locations as well.