Well you're extra lucky because Wynn is not centre strip, it's up the north end!
Bellagio usually do deals around the $159 mark so that's going to work out to around £100 a night at the current exchange rate.
June's not a bad time to go as far as prices go as it's damned hot so it's not a favourite month as such
Do you want to drive to Vegas from LA? If it's not something you really want to do, then fly, you can get a one way ticket for about £30-40 and it's a 45 minute flight, will give you an extra bit of time in Vegas
San Fran is a great city. If you want to go to Alacatraz I would advise booking boat tickets before you go, there are big queues out there. Have a look at the 'Blue and Gold line' website (if I remember rightly).
Most Vegas vets on here will tell you that the best deals are to be booked independently. Expedia do good deals in their January sale but they are fairly expensive the rest of the time in my opinion.
Fat Wallet is my favourite along with Travelzoo.com. If you want peace of mind, book through the MGM Mirage website for your dates and then keep searching for deals all the way up to a couple of weeks before you go, knowing you can cancel the deal with the Mirage with no penalty but at least you know it's booked, to keep the missus happy!
TC