Cross Country Drive

Oak Mountain State Park in Birmingham is pretty nice at least for the area. Did both the Exterra trail half marathon and the Powerman long duathlon there and enjoyed it both times. The heat that time of year should make it even nicer

http://www.alapark.com/oakmountain/

If you're going to Flagstaff, I highly suggest a day in Sedona. Some great hiking, Devils Bridge is one of my favorites. Bring your Camelback! There's TONS of others. In the 'downtown' area, there is a welcome center with park rangers. They have maps and suggest where to go based on your time, activity level, etc. Very helpful. We did a helicopter tour there with an old Army pilot, a doors off "adventure" tour and it was well worth it! There are also cliff dwellings to hike to.
 

If you want to go farther south than ABQ, Carlsbad Caverns is a nice stop. It's out the way from OK, but if you go south after ABQ , then you can hit I-20 and go to Dallas. 

Outside of ABQ, just a couple exits to the west, there is the Petrogylph national monument. It's RIGHT off the interstate, you can park and walk for an hour or two and see tons. Worth it and not out of your way at all. Just north of ABQ, Santa Fe is awesome.  

http://www.nps.gov/petr/index.htm

Just north of Santa Fe/ABQ, is Pecos National Monument. AMAZING views and old settlements. Also, just a short exit (maybe 15-20min?) off the highway, you won't be wasting all day to get there. 
 http://www.nps.gov/peco/index.htm

You can walk through some of them & go in the underground areas 

Have fun! We did several SW road trips, last one being last summer.

I'm confused on how the AlCan gets you to Seattle???  Don't you really need to take the Cassier and then go right at the split on that other hwy? (seriously can't remember the name   )

Another option is to go left at that split and take a tour of Jasper, BC then head south through northern ID and Montana.
Unless you HAVE to or REALLY want to go to Seattle, it's also a quicker route to Yellowstone (would take off two days, I'd think).  And an absolute BEAUTIFUL drive.   

FYI... It took me 3 fairly long days to get from Anchorage to SLC.  Of course, we were slowed down by mud on the Cassier before it was a paved hwy; however, I'd think with pavement, that would've only cut maybe 3 hrs off of that day.

After living in Fairbanks, I'm sure you're aware of it, but there are not (at least used to not be) many gas stations open before Memorial Day in the Yukon and northern BC. 
If you don't have a recent Milepost, get one. 

Option #2 for Seattle, take the ferry   (I considered it, but was too $$$ for college kid)

HAVE FUN!!!
You'll love SLC, I never left UT after stopping here for Grad school.  From rock climbing to skiing, and of course TRi's - we have it all

I am starting out right now via the AlCan. I am also looking at taking the ferry and weighing options now. This is going to be late May, starting around May 24, and be about 2 week trip. I want to visit Seattle because I have some college friends who live out there that I have not seen for about 8 years. Some of my other stops are more for breaks in the drive and also to visit other friends. Since, you live in SLC is there any good routes that I should do well I am passing through?

Stopping to stay long term on this drive will not happen since I have work waiting on the other end, Uncle Sam says I have someplace to be on the other end.

After looking at the map...  I suppose it's 6's (maybe slightly in favor of the Cassiar) to go to Dawson or not.  I'm sure it's changed a lot inthe 15 yrs since I've been there (and quite frankly, after Fort St John we were in whiteout conditions all the way to Whitehorse.)  I remember the Cassiar being muddy (was the week after Labor Day) but fairly desolate and beautiful.  Either way, carry an extra 5 ro 10gal can of fuel, just in case

Going from Yellowstone to SLC, I would suggest taking 89 to sight-see Bear Lake and Logan Canyon (Logan Canyon is probably one of my favorites for hiking - maybe b/c it was the first canyon I explored when I got to Utah).  There are very few lakes as pristine and Carribean like in the Rockies as Bear Lake.  Don't forget to look in your rear view mirror as you climb out of Garden City (and stop for a pic) the view is SPECTACULAR! (google it)

From Salt Lake to Zions, there's not a WHOLE lot.  I'm yet to explore Kolob Canyon, but hear it's spectacular.  It's off of I-15 and part of Zions but about 1hr from the main gate of Zions.  I'd suggest hitting it before actually finishing into Zions. 
I also just recently discovered Snow Canyon biking this past weekend in St George.  It's a mtn bike mecca!! (though I was on the road).

If you're into geology, Maple Canyon (about an hr off of I-15) is a site to see.  It has arches and odd formations all of conglomerate rock.  It's a rock climbers paradise with mostly jug holds   COMPLETELY unlike anything else I've ever seen.  BUT your time might be better spent at Zions.  I'd DEFINITELY allow at elast one FULL day to hike part of the subway at Zions.

As well, if you're heading southeast out of Zions, make sure you catch the "pink desert" (Utah's Coral Sand Dunes State Park).

Last but not least, the trail running in Northern Utah in AMAZING!  If you decide you want to stretch your legs somewhere b/t Yellowstone and Zions, let me know.  The China Wall in Logan Canyon is great, and there are NUMEROUS trails along the Wasatch Front (most of the snow at elevation should be gone by then).  My favorite trail is Great Western off of Guardsman Pass just north and above Brighton Ski Resort.  13 miles out and back takes you to vistas looking over Heber Valley, Park City, and Salt Lake City, through groves of Aspen and Spruce, and pass mtn ponds with various wildlife residents.

Let me know if there's any other info I can offer