I need to buy some new clipless pedals ASAP. First, some background info - I am NOT new to clipless. Started out on SPD's, then quickly upgraded to Time RXS Carbon pedals (using Northwave Road shoes)...which I have been riding for the past 2 seasons, but have grown to dislike. I found a buyer for my Cervelo Soloist Carbon, and as part of the sale I negotiated the pedals into the deal, since I don't like them anyway. The buyer is picking up the bike this weekend. Until I find a new bike, I am riding my "first" road bike - a Trek 2100 WSD with the SPD's on it (using Specialized MTB shoes). I cannot ride distances longer than 40 or 50 miles because my feet start to hurt, due to a combination of the small contact surface of the SPD's and the MTB shoes feeling too constricting in the toe box. SO...I need to get those SPD pedals off my Trek ASAP, so that I can go back to wearing my beloved Northwave shoes that have a wider toe box and are way more comfy. My Northwaves are a 3-bolt pattern shoe, so I am currently looking at the following pedal systems -

Shimano Ultegra 6700
LOOK Keo Max 2 (Carbon)
Speedplay Zero Cro-moly or Stainless Steel

Eventually, I will move the new pedals to my future new bike. Another concern for me, is...at some point down the road, I would like to outfit the Trek (since I plan on keeping it as my winter/rain bike) with similar but cheaper pedals that use the same cleats...so that I can keep using my Northwave shoes for BOTH bikes. Which has me leaning towards either the Shimano's or LOOK's, since I'm pretty sure that the same cleat can be used across their entire line of pedals...but I'm not sure if that is the case with the Speedplays. I do like the idea of the Speedplays being double-sided...but since I'm coming from single-sided Time pedals, maybe it would be best for me to stick with something I'm already familiar with? I just don't know. Help me out, ladies! I'm looking for feedback (both positive and negative) on the 3 pedals I am considering. I would like to buy or order something by this weekend...my feet can't take another long ride on those SPD's.

Thanks!

Linda