Not sure if anyone will see this, but :
I prefer Post Road and Buffalo Bills over any other commercial 'pumpkin' beer I have tried. I have not consumed Weyerbacher or Southern Tier, but I think I've tried the rest mentioned.
As for pumpkin ale brewing :
If you want pumpkin pie flavor, get a cookbook. Better yet, get several cookbooks, Mom's recipes and grandma's recipes and search the internet -- the recipes will reveal what combinations of spices work. As for the amounts of spices to add to the brew, look at other people's pumpkin / spice ale recipes, and work from there. If the ingredients / yeast predict a strongly flavored brew, use a little more spice. I don't measure anything, but I learned on the first try not to use lots of strong spices (e.g. cloves...). A 5 gallon batch of beer hides a lot less spice than a 5 gallon batch of stew! If it is too spicy initially, let it sit a month and try it again, repeat as needed.
Pumpkin -- Pumpkin actually refers to squash. In fact, the jack-o-lanterns we carve at Halloween are not ideal for eating, and not surprisingly, are not good for brewing. Restaurateurs have explained to me that 'pumpkin' soup/pie/pasta/etc rarely, if ever, contain the familiar orange, approximately spherical jack-o-lantern. Instead, they use a variety of other squashes. Similar to the spice advice, get as many squash or "pumpkin" -centric recipes as you can find and re-imagine them as a beer (I have flavor profile charts of malts and hops lying around for reference). My 'pumpkin' beer is based on a dessert recipe that does not produce a pie. Finally, if all grain brewing or mini mashing, mash the 'pumpkin' after first roasting the pumpkin. People love to claim that 'pumpkin' replaces grain in historic recipes and *none of them mash it*! By pound, squash is mostly water, so the sugar concentration isn't that great, and a significant portion of the sugars are in the form of carbohydrates -- mashing will turn that into fermentable sugar. Liquefying the roast squash with a blender or food processor may be a good idea, but I've never tried it. (this year...) Also, various squash are available most of year, so 'pumpkin' beer can give that Thanksgiving reverie practically all year.
The best article on 'pumpkin' beer I have found is :
http://www.absbrew.com/index.php?act=viewDoc&docId=15Finally, whenever this year's version of my SaazSquash (har har) is brewed and properly aged, I'll share some of it (provided that it lives up to the hype -- people in other states ask me if I brought any along when I go visit.)