If you are in London, probably the best selection of fragrances in one place is Harrods. The only problem is deciding what to ry before your nose burns out.
Thanks again for all of the recommendations, guys. A quick update...I am fortunate to have access to some of these colognes locally (one thing I absolutely love about Europe that was pretty hard to come by in the US) so I have done a bit of research.
I was not able to find any of the Creeds recommended here, but I did check out the price on some. I believe they were around 160, so no dice on the European discount. I also came across some Penhaligon's: Blenheim Boquet and Endymion. While BB was not to my liking, I was really intrigued by Endymion. It is definitely for cooler weather and far too sweet for my liking, I still liked it quite a bit, and it has piqued my interest about the house in general.
I tried Eau Sauvage and while I definitely thought it was very clean smelling, there was something else about it that I really didn't like. I think I have experienced something similar with Tabac if that helps at all. I checked Tabac out just because it was so popular here, and thought it smelled like overly strong cheap old man cologne. YMMV, of course, so no offense!
I tried AdP Colonia Assoluta again and did not like it as much as before. I think it was because it was a colder day and it just "aged" differently. Whereas on a warm day there was this intoxicating richness, last time I just got "Love My Carpet" out of it. Heart=broken! However, I have re-discovered AdP Blu Mediterraneo Cipresso di Toscana...I fell for this scent once before, made a note that it was called "Blu Mediterraneo," and then went home and realized that there were about 8 different Blu Mediterraneo options to choose from. Anyway, I feel like this captures that same warm weather intoxicating richness, whithout some of the other AdP overtones that I am not as excited about.
So...I am definitely leaning toward Cipresso di Toscana at the moment (any thoughts on that?), but will wait until after my London trip next weekend to make up my mind. I am particularly looking forward to checking out Penhaligon's Racquets and Truefitt and Hill's Grafton, but am hoping to come away with lots of samples from both houses (and possibly Trumper's, as well).
Thanks again for all of the tips...I will continue to experiment and will let you all know when I have made up my mind.