You’re not going to find (1) a small, intimate college that also has (2) huge course selection, plus (3) great financial aid, yet (4) isn’t too selective. So where do you want to compromise?
Amherst (including the available consortium courses), or the Ivies, can give you the first 3.
St. Olaf can give you #1, maybe #3, and #4.
Many state universities can give you #2 and #4, and possibly #1 within an honors college or small department.
A couple of women’s colleges (Bryn Mawr, Mt. Holyoke) could come close to meeting all 4 if you exploit consortium courses.
It seems to me that #3 is non-negotiable. You must be able to cover your costs.
You manage #4 (admission selectivity) by building a balanced reach-match-safety list.
So you’re left with the problem of balancing size and course selection.
The consortium LACs are pretty good for that.
Mt. Holyoke, Smith, and Amherst span a fairly wide selectivity range, but all claim to meet 100% of demonstrated financial need. All three can compensate for their own size limits with courses at UMass, which has a very respected CS department. The Claremont consortium is good, too (although it lacks a big research university with strong CS/math).
But, if you’re admitted with good aid to a fabulous university for the programs you want, maybe you drop your concerns about size/intimacy? Then try to find a small circle of friends you like and a good faculty advisor/mentor for support.