They're fairly similar, should go well together.

Hope you've got plenty of space for them!

Resin

I agree. They will go well together. I have some of each in my yard. One difference between them is the growth rate. Shearing the sides of the tree will tend to make them dense and allows control of their circumference and shape. They make wonderful privacy screens if you have the space.

Are you prepared for a tall tree? Some of mine were planted in 1983 and are approaching 100ft. One planted in 1991 is about 30 feet. One planted in 2000 is about 15 feet (planted in hardpan). Neighbors planted in 2002 (they water heavily) and theirs is about 30 feet. They can be rapid growers.
-Hal

Aptos blue has a nice blue-green leaf, it's branches tend to bend downward toward the tips. It tends to be a bit akward or gawky when it's young but fills out nicely as it ages. Soquel is a brighter green, it's branches turn upwards toward the tip and it's a nice full plant from the get go (usually). Other than that, they'll both grow around 15'-25' in diameter and reach for the sky in height.

Regards,
Dan

Aptos Blue is supposed to tolerate standing water for brief periods better than the others. I planted 2 tiny Aptos Blues from forestfarm.com last September and they have doubled in size and are doing well -- better than any of the other coast redwoods I've tried.

Had a Soquel, very pretty, planted it last year in a creeklet and it drowned. They want watering but don't want to sit in a pool. They don't like below-freezing temperatures, and they burn when young in hot sun. Hard to grow but gorgeous tree if you can get it to survive.

Neither is dwarf.

Here is a link that might be useful: APTOS BLUE COAST REDWOOD

Both are Saratoga Horticultural Foundation introductions dating from 1975 or earlier, so there should be some 30-year-old specimens around.

Here is a link that might be useful: SOQUEL COAST REDWOOD

I just planted a 15 gal. Blue Aptos in the back corner of my lot. We live in a typical new development in Roseville (Sacramento) which means everybody is very close. An arborist came by and said I'd be fine with the space; now that it's in I'm not so sure. How invasive are they? A problem for the backyard neighbor's pool, which is about 15 feet away?

Shade and litter would be the only problems for the pool. These annoyances are not going to commence overnight. First the tree has to get big enough.