I would recommend the Sun Valley over the Autumn Blaze.

http://www.usna.usda.gov/Newintro/somerset.pdf

Alhtough how Alkaline is "really alkaline"? The Sun Valley/red maples would "prefer" slightly acidic. If its off the charts alkaline and if its a very dry spot you may need to go to the Autumn Blaze.

Are there possibly any other choices?

DO NOT, DO NOT and I repeat DO NOT ammend the soil for ANY tree.

If you are working with a slight slope, put all the native soil back and top dress with a few inches of a organic compost, be sure not to put it next to the trunk.

whaas thanks for the response. I wish there were more options around. Most of the nurseries around here carry the same stuff but since it is the end of the season the selection is really limited. I found a 2" caliper sun valley and all the nurseries have a lot of Autumn blaze. I may also be able to get a 2" caliper october glory but I don't like the OG color as much.

I know what your saying. I'd make sure you ask for a discount, or make sure there is some type of coupon. Its not in the nursery's best interest to overwinter B&B product.

2" caliper would be a good size. Just make sure you have a well branched tree with a noticable central leader. Try to avoid co-domindate leaders.

I would go with Sun Valley over the October Glory as well.
The more I read the more I see that Red Maples are going to be subject to chlorosis (yellowing of leaves) in aklaline soils. So if you have anything more than slightly alkaline looks like you need to go to the Autumn Blaze.

Fall color may not be as brilliant and it is a "little" more suseptible to breakage (good branch structure and proper crotch angles will help alleviate any breakage problems). I wouldn't really worry about it, unless your very prone to severe ice storms or severe winds storms (winds gusting more than 50 MPH).

But, Autumn blaze is faster growing and much more tolerant of drought and alkaline soils.

I bought the Sun Valley Maple and planted it today. I think it is a really pretty tree. I am posting a photo here for those looking for a Sun Valley Maple. This is a 2" caliper. The photo does not do justice to the leaf color. These leaves literally glow.

Here is a link that might be useful: Sun Valley Maple 2

I almost bought a Sun Valley maple at a nursery in my area, saw it in full fall color and if you like red it's the one. I have Autumn Blaze maples, many get a pinkish red vs. a true red although I do have one that gets a more pure red with even some orange on some leaves which is gorgeous. What turned me off of the Sun Valley maple was the leaves were small compared to other trees of its size. I prefer larger leaves. The leaves almost looked more like a Japanese Maple but not quite that small. The tree was about 10' tall.

Looks good...give it a ring of mulch (or strip) and your ready to go.

I have both and let me tell you that the Sun Valley this fall has been amazingly beautiful. I've been so impressed with it. The AB was really muted and dark maroon. Both have been in the ground 3 years and are 7-9' tall or so.

I have a Sun Valley Maple and no they do not produce seed pods. I have a 3-4 year old tree. This was taken just after it was planted at approximately 2 years old.