Bike Purchase questions

I'm just looking for people opinions,  I'm just trying to get some ideas to help me make my choice.

So I have approval from my wife to get a new bike.  I think I'm more concerned with the cost than she is.  The only stipulation is that this has to be it.  I can't come back in 6 months and say I don't like the bike I want a different one, or I should have gotten the tri bike instead of the road bike etc.

I will most likely undoubtedly do more social club riding than I will do triathlons, but I still want a bike that will be competitively fast for triathlons.

I have decide on getting a Cervelo, and I have about 6k to spend.
Here are the options I have been mulling over, what would your choice be with these options.
S3 with SRAM-Rival approx $5900.00
S2 with Ultegra-SL $3900.00
      with Dura-Ace 7900 $5500.00
      with SRAM-Red $5400.00
RS  with Ultegra-SL $3500.00
      with SRAM-Red $5000.00
P2C with Ultegra-SL $2700.00
       with SRAM-Red $4400.00

Since none of these bikes are slackers, they are all a quality product, I am wondering if I should just buy the most bike I can get for my money, and then I have that one bike for both activities.

So If I did that I would be getting an S2 or S3 with SRAM or Dura-Ace and I would be needing to use it for both recreational club riding and my triathlons.

Or do I go down a model and down on the components a bit.
If I did this I could get 2 bikes for almost the same price range.
I was thinking of getting the RS & the P2C.
Then I would have a bike for each activity and wouldn't be committing myself to having to use 1 bike for both activities.

Help, I can't make up my mind.  I keep waffling back and forth.

Thanks

Scott