I am in the same spot - I have one H&K with a proper set of night sights, and two that I do not currently carry because they don't have night sights yet.
From what I've seen, the options are as follows:
Trijicon HD's Trijicon HD? Night Sights
I want to get a set of these to put on my P30L and see if I like them. If they are as quick for the eye to pick up as advertised, I may start switching my other pistols over. I like the idea of speeding up front sight acquisition without sacrificing too much precision. I believe that the HD's have only recently been introduced for the HK's, so you may have to wait a while if you order a set. The Trijicon site says that they are 8 weeks away from shipping....but who knows.
"Vanilla" Trijicons Trjicon Bright & Tough? Night Sights
I run a set of Trijicons on an 870 that I have - and after six years of use as my "Jeep gun", they are still going strong.
Meprolight Tru-dot Meprolight, Heckler & Koch
I have a set of these on my USP-C, and I like them. Bright, sturdy, they work just fine.
XS-sights XS Sight Systems - Sights
I have no first-hand experience with these, but I've heard a lot of people say great things about them for defensive use. Apparently you give up some precision at longer ranges, but an a P2000sk that's a carry gun that may not be an issue. I'm considering a set for my S&W Shield.
Heinie Straight Eight sights Heinie Specialty Products | High Quality Replacement Pistol Sights
A lot of high-end 1911's seem to come with straight eights. In my mind they are closer to traditional target sights than most "combat" night sights - but again I have no first hand knowledge.