Well, I've done a few thousand-mile days
and I'm just full of useful suggestions.
First thing is to examine everything that sits between you and the seat itself. No jeans with seams, no bulky underwear, no cotton, no padded bike shorts, etc. Any of those things will increase sweating and rubbing and thus add to your overall discomfort.
Personally, I like Aerostitch Darien Light Pants
(waterproof, comfortable, and no seams to sit on) and LDComfort Undergarments
(breathable, wicking, extremely comfortable, and no seams to sit on). That's the only thing that I'll wear on any ride over 2 hours or 100 miles (well, that and something on top, as well).
As for seats, the reason you squirm about now is because the factory seat is so poorly shaped with no real support. A well-shaped seat built for you by a talented saddle maker will support you properly such that you won't need to squirm around.
Your choices for quality custom-built aftermarket seats are:
(Shasta Lake, CA) consistently gets great reviews for comfort, quality and customer service. Besides adding a bit of height (as expected with any custom seat designed more for comfort than looks), I don't think I've ever heard a single serious complaint about them. They also use an internal leaf-spring system (developed by the senior Mayer father) that works very well, especially for larger/heavier riders. And they have a removable backrest option that no one else offers.
Bill (Rocky) Mayer
(Ojai, CA) makes a quality seat and generally folks are very happy with his work. I have almost 200K miles on his seats across two Beemers.
(Anderson, CA) also makes a great seat and his customers remain very loyal. He does occasionally get some complaints about customer service (mostly a lack of communication), but he's basically a one-man shop who focuses more on the art of saddle making than paperwork and admin stuff. But everyone who gets one of his seats raves about it.
(Tucson, AZ) is run by Ron Miller from this site. He uses a variety of modern foam layers and breathable outer fabric to create a seat that more evenly supports the rider. He has quite a few fans on this website.
(Kingston, WA) is another, smaller provider. The few folks I know that have them do like them.
The other choice is to go with a pre-made replacement seat. These are usually cheaper and can work well for some riders, but aren't really on the same level as a full custom seat made to your dimensions. Still, they do have their admirers, and since it's a complete replacements seat your factory seats remain intact.
Your choices for replacement seats are:
(Jacksonville, FL). Most folks seem happy with these.
(France). They are based in Europe, although they do have a US distributor.
(Hollister, CA). They make rock-hard seats that take a long time to break in. Some folks do like them, but way too many folks complain about the comfort, the quality, and the customer support for me to ever give them any of my money.
Any of these options should run roughly $500-$600, although custom fabrics/leathers and other options can obviously add to that cost.