It takes a LOT of energy to get something anywhere close to C. I can’t remember the exact numbers but I recall it would take 99 kg of antimatter to accelerate 1kg of matter up to 0.5 C and then stop it again. Nearly every sci-fi novel vastly underestimates the mundane logistics of interstellar travel. It may turn out to be feasible but not economically viable for anything but long term hibernation ships.
[QUOTE=Epimetheus]
How will 2Gs make you older? Just the forces involved?
[/QUOTE]
Wear and tear.
Conversely, if you accelerate at 1/2 G, you’ll be younger when you arrive. 
If you pass the speed of light, you arrive before you left, which makes you temporally younger as well.