I agree with the guys, that a second pistol in 45 caliber, or a 357 in 6 inch revolver, is the way to go to round out the shooting experience.
a smith 686 or a 586 is good for ppc, and revolver handling is a skill in itself. nothing like a magnum experience from the usual 9mm or 40
the 45 is quite pleasant to shoot, and the single action trigger can be crisper than your beretta, just remember the safety in the frame, thumb down to fire, while the beretta is usually safety in slide, and thumb flip up to fire.
the kimber is great, never owned one, but also good things about the sti trojan, smith 1911, springfield, all should have great single action triggers
(i wouldn't go polymer yet)
you are still in the min. $900 to $1200 price range.
prproulx is right on about the history and gi thing, but i think he might agree with me that for your first 45, don't go with minimum gi specs, because you will think later of getting one with at least an ambi safely, better fixed novak or adj sights, beavertail safety, etc, get that in your first .45 rather than kick yourself afterwards for not buying all that in the first place.. I did. lol