They want to return the first stage to land in the future (at least when possible, depends on the launch trajectory etc iirc). So high waves won't be an issue when they start returning the rocket to the launch site.
Also, I guess if reuse becomes routine and they need to land in the sea (because there aren't enough fuel to return to land) they could build a huge vessel capable of handling high waves.
If reuse becomes routine and the necessary authorities approve, they'll land on solid ground near the launch site. The floating rig was just for the initial tests.
In this specific case they don't actually have enough extra fuel to do a boostback burn, meaning the landing site has to be significantly down range of the launch site (400 mi IIRC).
Also worth noting: once cleared for landing on land, SpaceX can move their launches a few hundred miles West and omit the barge, landing the stages down-range at a coastal landing facility. Added bonus here is that returning cores via road is a heck of a lot cheaper than by sea, and you avoid that nasty salt-water-on-fancy-metal action.
Near the launch site? That seems a little ambitious, and expensive. Are they planning on doing a u-turn in high atmo? The energy required would be massive. Or are they planning on doing an orbit of some sort?
Doesn't the falcon heavy animation show the stages all landing at a different facility?
Given that most every launch will point in a different direction from the launch site (different inclinations), boats would seem the best option. They could then haul the stage back to base by sea.
Yes, it's called a boostback burn, and it's been a part of every landing attempt thus far. The first stage has burned so much fuel at the stage separation that it takes much less to return it home than it did to accelerate it. You are correct though that it limits the payload capacity of the platform.
I believe the Falcon Heavy animation shows the rockets returning to the launch site.
This launch was/is going to be the first one without a boost back. Because of DSCOVR's mass and destination (Earth-Sun L1 point), there isn't enough fuel to make a boost back burn. That's why the barge is ~650 km off the coast[0] instead of the 350 km it was for CRS-5[1].
They've already launched from California, at Vandenberg AFB. They've begun constructing a drone ship for landing future rockets launched from Vandenberg, named Of Course I Still Love You (the one currently in use for KSC launches is called Just Read the Instructions).
And yes, they are currently constructing a new spaceport in Texas near Brownsville at the far southeastern corner of the state. Completion and first launches are anticipated in 2016. I'd guess they might use the current drone ship for landings from that one as well, but a lot can change in 2+ years so we'll have to see.
I believe that the Falcon Heavy animation showed the stages returning to the launch facility. SpaceX's primary goals with reusable stages are reduced cost and reduced time to refurbish, and landing at the launch site is a big part of that.
It looks like they indeed perform a u-turn, with the proviso that some of the return is accomplished by pushing higher, increasing orbital period, and waiting for the earth to rotate underneath.
Also, I guess if reuse becomes routine and they need to land in the sea (because there aren't enough fuel to return to land) they could build a huge vessel capable of handling high waves.