I would also put in a plug for the Comfort style pens if you like the smaller 7mm tubes and cross refills. They're a bit larger and more comfortable to hold.
Slimline pro, Cigar, Designer, Gatsby, Polaris and Executive styles (PSI names I'm still more familiar with, don't know all the alternative names yet) are nicer alternatives and use the Parker style refills that I personally prefer.
In then end, think about what you like in a given style and think about whether your recipients will like that as well, or do the appreciate different qualities in a pen? Does the preference lead toward twist style or click type pens? Single body or double? Large small or medium in size? Once you answer some of those questions, you'll have narrowed your search down considerably.