Juicy
The one mistake I made when I bought mine was not getting air-con. It's a personal thing but I know now that I would have preferred it. I also think it helps with resale speed - if not necessarily price.
As far as colours are concerned I think there are very few that don't show off the car well in the flesh. For instance, even though I don't like portofino blue, there are some on this site that are undeniably gorgeous. I think my sprint blue takes polish fantastically well although it isn't subtle.
As lots of people have said you need to see good examples in the flesh or just get the mechanically best car you can afford and learn to love whatever colour it comes in
Just for your info here is a break down of the colours in the club from Kayjay's list:
Metallic Light Red 13
Racing Red 282
Metallic Dark Red 78
Dark Red 11
Iridescent Pearl White 12
White 6
Broom Yellow 207
Metallic Energy Green 17
Metallic Chamonix Green 39
Metallic Crono Grey 26
Metallic Scots Green 94
Metallic Blue 100
Sprint Blue 178
Metallic Portofino Blue 110
Black 42
Metallic Vinci Grey 36
Metallic Black 32
Metallic Steel Grey 146
Metallic Moon Grey 77
Metallic Electric Blue 63
Metallic Ink Black 149
Rosso Red 36
Which is probably as good an indicator of relative rarity as you'll get.