My first thought would be that you might want to take advantage of this promo:
http://dmn.delta.com/offers/getmore/ which would get you 390,000 delta miles. If you have an extra 10k miles already (or were to use an Amex advance of MR) you'd end up with 400k, and enough miles for 4 premium round trips if you manage the find low price availability @100k each, or 4 medium awards in regular class @ 90k each. (You each would also get silver status on delta, but that's not worth much except free bag checking, especially if you rarely fly.)

That said, there might be better deals out there, since skymiles aren't known to be the most valuable.

Another suggestion is that flights booked with miles are generally more flexible in terms of stop-overs and open jaws than the very discounted fares you might be used to. So if you are going to be traveling around the country, I'd recommend you arrive and depart from different airports (in an open Jaw) so that you don't spend some of your time backtracking through the country. And you might want to consider if you are interested in a stop-over for another visit on the same plane ticket.

You might want to check out the membership rewards forum here, as well as try and find availability before you move your miles to a particular carrier.