Congratulations on the new (to you) 990!
If the source in question is a cable box, my experience has been that there is no benefit in using DVI/HDMI over using component. If I were in your place, I'd use component video from the cable box and the DVD player, leave the TV on one component output, and make your wife's life easier (and thus yours as well) without losing any video quality.
As you point out, if you move to the OPPO BDP-83, you can then switch to using the DVI switching with those two DVI/HDMI sources and keep things simple for the family.
You might also consider a good universal remote with macro capabilities (a Harmony or Universal) at some point in the future - if your TV has discrete input commands, a few slick macros and carefully-labeled buttons can make life much easier. I have used several Universal remotes (currently an
MX-900 with an RF receiver, but before that an
MX-700 and an
MX-500 ), and having the remote properly set up makes it possible for me to have a pretty sophisticated setup without my wife kicking it (and possibly me) out of the house...