First time on QR, read the Wiki but not the whole thread. I would appreciate comments/answers.

Flying JNB-DOH-LAX. Got coach for 3 for 40k miles, which I thought was a pretty good deal (nothing else available at the time). Yesterday I was able to upgrade JNB-DOH, for all 3. So now paying 75k which is Business for the entire routing, even though only coach for DOH-LAX (a quick 16 hours). Two questions:

1. Other than watching inventory and hoping to find a business class seat on DOH-LAX, are there any other options? For example, can I be listed for upgrade on day of flight since I have already "paid" for business class? Or is it only U inventory even on day of flight?
2. I now qualify for the "stopover" hotel deal of $28 for a 5 star hotel in Doha. Which hotel should I select? [not on a QR ticket, don't qualify - still interested in hearing about good locations for one evening ever in Doha]