Getting on for 100 pages now and I'm starting to think about next summer. The reason I am is because there is a 20% offer expiring soon on Virgin buy miles. I wrote a while ago about optimising the promo, but an example would be my current situation, where I have some miles, but if I hurry up and take the bonus offer, I can buy enough miles to fly Upper for £600. Airport duties will come to about £500 or so, so £1100 for Upper when many ice creams will pay nearly that just before the off in muggle class, and quite a bit more than that in premium.
I think there's enough gold in the thread for people to get a lot of good advice, but I still see people make a hash of it, however you look at it.
1. Start yourself off with a good benchmark. You won't know if something is a great price unless you have something to compare it with. Suggest Virgin flight and hotel direct (via smarterVegas for discount) See what that price is and now you have something to beat.
Note that tweaking that benchmark is largely a personal thing.... sure you can fly with 2 stopovers if you want to save £100 or you can stay in a dump to save £100. There isn't a right or wrong here, everyone can choose to what extent saving £100 means something to them, so it is tough for anyone to help.
The areas which people can be helped with is when they have decided a budget and got an itinerary in mind. People often say "I've got IP/Harrahs/Excal etc because it's cheap" - that's fine to choose somewhere to suit a budget. However, most of the time, a little bit of googling would have got you a decent 4* instead of a bad 4* - perhaps PH for the same price. Whilst a lot of things are down to personal taste, I don't think many would say the IP was better than PH for the same $$.
2. In just about every trip I've ever made, I have saved myself several hundred by keeping an eye on things. I'm not sure how much you earn, but if it isn't several hundred an hour, spending an hour online to save yourself that sort of $$ is surely time well spent. As others have pointed out, tweaking the flight dates by a day could be £300 right there. Or searching a few 3rd party suppliers might beat your benchmark by a few hundred.
It largely boils down to how much you can be bothered to do it ~ I just smile when people can't be bothered to spend 10 minutes doing it, but then when they get there, they don't mind spending an hour walking from the IP to the Tropicana to make use of the $2 buffet coupon.....
Note that prices really do jump around - just because you looked once, doesn't mean that if you look the next day the prices won't have changed significantly..
3. Depending on your flexibility, you can make changes as you see fit, either getting better hotels for the same money, or same hotel for less money, etc. The big difference is cancellation rights ~ if you see a hotwire price you like, great! But you won't be cancelling, so make sure it really is what you want. For those that have to be back at their desk on Monday, this isn't so bad, but it is annoying if you book and then offer of the century comes out somewhere else. So if prices are identical, you should book without using a 3rd party, so that you have full cancellation rights.
4. Signing guestbooks, liking pages on FB, will get you offers coming in. Having an MLife account or Total Rewards account will get you offers for all but the nittiest/anti-gamblers. Trawling through smartervegas etc and as many 3rd party (Orbitz, lowcostusa etc etc) sites as you can think of and be bothered to check. Or just be lazy and give Marky some half-baked incomplete information and let him puzzle it out for you

As a rule, booking during a Virgin Sale and getting a heavily discounted room code is going to be a tough benchmark to beat. But still worth trying.