I think I'd be tempted for the extended stay in the Al Safwa lounge. Then again, I couldn't care less about the F1 or a mosque, and I hate going to Westfield White City down the road from my house so the idea of spending any time in a shopping centre while I'm on holiday really negs me out. I have been and I stayed in Raddison Blu Yas Island when I was in Abu Dhabi and I was happy there. In the hotel.
But, each to their own. If those sorts of things sound appealing to you, maybe the stopover. Al Safwa looks like the dogs though. I'll be there for the first time next month when I do LHR>CAI>DOH>JFK>FLL-MIA>EYW>JFK>CAI>DOH>LHR!