I'd really just start with Google Maps. You can get directions and times between cities, or build a whole itinerary (LA to Vegas via SF or whatever you like).

maps.google.com

> 26th Feb 2014, is the weather going to be ok as in warm
> (hopefully enough to wear t-shirt), not rain all the time.

In the San Francisco Bay Area, it most likely will be wet, too cold for T-shirts, and dreary. It COULD be warm and pleasant, but don't count on it.

> Fly into where????? LA or San Fran..., which direction do I head?

Fly into the city which has the best combination (price-wise) of air fare and car rental. Pick up the car and do a circle from City A to City B to City C and back to City A, returning the car to City A.

You MIGHT save money by flying into San Francisco and not using a car for either the first couple of days or the last couple of days of your trip using public transit. In the other two cities, you'll pretty much need a car.

Note that, from 2014 March 4 to March 8, and expected 150,000 convention goers will be descending on Vegas.
http://tinyurl.com/cpkfpbr
Do NOT go near Vegas during a major convention like this: you'll be LUCKY to get a flea bag room for $300 a night.

One last thing: BEFORE you ask us, "What things should I see?", *PLEASE* tell us what YOU want to experience during this trip. We can tell you what WE like, but YOU might find our likes a complete bore. The more specific, the better.

In the San Francisco Bay Area, it most likely will be wet, too cold for T-shirts, and dreary.

Only when it rains. It is often bright and sunny between storms--which hardly occurred this year--but not T-shirt weather. However, February is traditionally a wet month, and many people are reluctant to drive the along Big Sur in that season.

To know what to see, a guidebook might be in order, Fodor's California perhaps?

First off, are those the right dates? Feb 26 2014 is a Wednesday and it just seems odd to have time off starting mid-week and ending mid-week..If you are indeed starting/ending your vacation mid-week, that's a good thing usually for Vegas as hotels are generally much cheaper mid-week than on the weekends.

Anyway, if you want to end in Las Vegas for 3 nights, it probably makes the most sense to fly in/out of Las Vegas then. I would guess the combo price of flight/car from Las Vegas will be comparable or better than San Francisco or Los Angeles.

Really your other option is to fly into one of the California cities (San Diego, LA or San Francisco) then drive up or down the coast and fly to Las Vegas from wherever you finish the road trip.