I live in the "east valley" although on the opposite end of it from Scottsdale; unfortunately I don't know that much about hotels or resorts and such. I am not personally aware of any resort type places that are in the same direction as the Arboretum...
@IFlossU might have some thoughts?
If you're venturing east (the east side of Phoenix I mean!) you might also check out Goldfield Ghost Town... definitely touristy but it looks fun to me (I've never been).
Also no specific thoughts on Presidents' Day Weekend unfortunately... although for a lot of people February is a really good time to do things here because a lot of people are freezing in other parts of the country. (We Phoenicians are also freezing but that's because most of us have zero tolerance for cold... myself included). Could be busy with snowbirds and such but I'm sorry I don't know about activities and crowds.
I will say when I was hiking a lot that prime hiking season was between November and February, so definitely expect to see people on the trails.