Are you trying to tell us you have a fat a...?
A B17 Standard should give you plenty of wriggle room.
Saddles such as the Pro and Swift are supposed to be better suited to racier riding (changing position more), but being narrower might not offer you as much comfort.
I move from drops to tops a fair amount, but have never found my B17S to be compromised.
As a (my) rule of thumb: Brooks for distance, Selle San Marco Rolls for speed.
Either way, if you look on
Ebay you'll see that it is hard to lose money on a Brooks: re-sale values are rock-solid, so much so that it is hard to recommend trying second-hand first.