The reason I mentioned $50 for two cab trips is that the few times I've taken a cab -- to and from both the Mirage and Treasure Island, it ran somewhere between $15 and $18. With luggage handling and a "decent for Vegas" tip, it seems I've always ended up handing over $25 total each way.

Re: Rental Cars - also make sure to check for coupon codes. Costco usually has a good set of coupon codes for car rentals - I've been using their code for Alamo rentals in Vegas, and those have been cheapest for me.

Re: O seating - I've sat in the cheaper seats and it was fine. I don't think there's a bad seat in the house, except for the "obstructed view" seats. If you get too close, you may get wet and you don't have a wide enough view to take in everything. Make sure to get there early as there's some audience participation that goes on pre-show.

Re: Must See on the Strip - The Bellagio fountain show is a "must"; as is their conservatory. I suppose the Mirage volcano is worthwhile. The TI Sirens Show probably isn't worth the wait, but it's something to see. A trip up to the top of the Stratosphere is great for a good view of the strip.