The SkyTeam presence is actually pretty limited. CO only flies to HNL (soon to be down-guaged to a 757), CLE, IAH and EWR; I'm pretty sure that they killed their LAX-Mexico mini-hub operation on ERJs, though maybe not. NW flies to HNL, MSP and DTW (and maybe MEM). DL is building up, but isn't all that impressive overall, as most of the flights are on ERJs or via SLC, CVG or ATL. There are a couple transcons a day, too.

If you fly the non-AA codeshares on Alaska you can credit to CO or NW and get EQMs, but there are a large number of AS flights that are actually AA operated, so you have to be careful there. UA and AA have a much stronger presence in LAX and may serve you better, both for transcons and north/south runs out west.

If you are going to pick a SkyTeam partner out there I'd go with NW. CO will honor the elite status same as their own, and NW has more partners and earnings bonus options.

S.