It seems a shame that the year the Cards had a lot of cap room, there have not been many star quality players available. Granted, Colvin would have been a good pick-up, but IMO Holliday isn't "all that". An upgrade in AZ? Yes, but "all that"...no. I would have rather have had Sam Adams (or a 6 pack of Sam Adams). Think about it, the best FA may very well have been David Boston (if he keeps his nose clean).
Taking into account the lack of "premier" free-agents, I would like to see the Cards bring Jamir Miller in for a work-out (if he hasn't signed elsewhere). I have read that he has put some weight on in order to play the defensive end position. If he has fully recovered from his achilles injury (if that is a possibility), he would be an upgrade over what the Cards have there right now IMO.
There will be those who say, "Jamir will never play for the Cardinals", but if the Cards are really trying to change their image, what better way than to bring a player back that they once had issues with. IF he can still play, it would at least make up for one of the Cards losses over the years.
Just my opinion.