While I was looking to replace the mid-90's Raleigh MTB that got me back into biking, I encountered the gamut of different sales techniques. Finally after much searching, the last place I thought I'd buy a bike from actually had the most competent staff.
During that search I thought "I wish there was somewhere I could find that had a list of shops who knew what's best for bigger guys". Well, such a thing doesn't exist - but why not post in this forum? Post reviews of shops who know how to fit bigger guys, and do a good job of it.
Here's mine for Lincoln, Nebraska (in descending order):
Scheel's All Sports, 27th and Pine Lake Rd: I stopped here to pick up a SureFire bulb, and left with a Hardrock ready to be picked up that evening. The person you want to talk to is Andrew Kirchner (sp?) who knows just about everything there is to know about Specialized bikes. That's the only downside - the only real brand they carry is Specialized. BUT, they take the time to fit you, let you try out as many bikes as you want, and will add components (better brake pads) to make the bike better for larger riders.
In fact, I was downright torn between the '07 Hardrock and '07 Rockhopper. In the end, Andrew actually told me to buy the Hardrock as it has 36h wheels with heavier guage spokes. Gotta love a salesperson who sells you the cheaper bike.
Their service department is also top-notch, and very affordable.
Monkey Wrench Cycles, 1225 P St: VERY friendly guys who really know their stuff when it comes to bikes. They can order in just about anything, and have good recommendations. I've been in there twice, both times I've been very pleased at their suggestions. Also know what matters to a bigger rider, and seem willing to take the time needed to please the customer - whoever they may be. I'll be going back to buy some sort of road-ish bike soon.
Blue's Bike and Fitness, 33rd and Pioneers Blvd: This place is highly hit and miss. The day I bought my Hardrock I went back to do a final ride on a Cannondale F400, but the employees working basically ignored me. So.. I ended up with a Specialized.
HOWEVER, there is one or two employees who are extremely knowledgeable and willing to let you ride their entire inventory until you find the bike that's perfect for you. I probably rode at least a dozen bikes over a several month period, working with two of the sales people. One was a man in his 30s or 40s and a bit of a bald spot, the other a young tan early 20's who really goes above and beyond.
Due to the hit and miss-ness of this shop, though, I can't really highly endorse it.
Bike Pedalers, 33rd and "B": GREAT shop for service, and they have a great selection of used bikes. They are hugely service oriented, you won't be outside this shop for more than 2 seconds before someone is willing to help. All the employees bike, and know their inventory well. They also know what is important to a larger rider, and are willing to work with you.
However, they get a lower spot on my list because in new bikes their selection is somewhat limited for larger riders. Which is too bad, I'd love to buy a bike from them.
Cycle Works, 27th and Vine: I went there twice, the first time I was totally ignored and the second time I found a pretty decent rep. The employee knowledge is 100% hit and miss, so give them a quick quiz before you talk too much. They mainly focus on Trek, Giant, and Bianchi, so the selection is a tad limited.
And that's all the ones worth mentioning in Lincoln. Post yours!