I think, but I'm not sure (someone else will be able to confirm) that you can have both speakers and headphones plugged in to the Sound Blaster Ti-HD.
Other cards I know you can do that with would be the Sound Blaster Z series (Z, Zx, ZxR) and the Xonar ST/STX.
Of those, the Ti-HD is probably the best value (not sure if there is a built in headphone amp, though); followed by the Xonar STX (though both the Z and Zx are cheaper than the STX).
If money is no object, and you have the open slots, the ZxR is supposedly a wonderful card, but at $250 it might not be worth it.
If it were me, and again money is no object, I would go for the ST (PCI, $208ish on Amazon) or the STX (PCI-e, $190ish on Amazon). That would be because I would use the built in headphone amp.
Note I am only suggesting cards where you can have both headphones and speakers plugged in to the rear of the card. I have issues with the front inputs on my case, therefore I do not suggest any cards where you might need to do that for your headphones.
If you don't mind swapping cables every time you want to swap between headphones and speakers, the Xonar DG is a great 5.1 card at $30.