I actually tried to figure out what the sweetest D3 and D2 recruiting jobs were. It obviously depends on who's around you, but I don't mind posting what I came up with and getting comments/criticism.
D3:
1. Colorado. This, I think, is fairly undisputed. And what's around you doesn't much matter.
2. Palm Beach Atlantic. This too.
Beyond that, other factors come into play, but these areas look to me like they have potential.
*Georgia/South Carolina. There are 25 D2 schools between these two states and only four D3 schools, so this is prime dropdown/pulldown territory. And once you get the prestige up and half your recruits are generated based on the D2 population, it's just plain ol' prime territory. Little competition. I'm not sure what the best place to be is. Piedmont is the most centrally located, but Oglethrope and Emory both are within the 70 mile radius of Atlanta. This choice loses some value if the ODAC is a super-conference with lots of bonus recruiting money. A lot of those schools are within 360 of both states, so they can out-muscle you--even with a distance disadvantage--if they have enough extra cash.
*Nebraska Wesleyan. This is speculation, as I've never coached here, but there are eight D2 schools between Nebraska and Kansas and just one D3. Also, you're the closest D3 school to Colorado, although I'm not sure exactly where the mile borderlines break here. Google maps mileages are quite different than WIS mileages. This becomes a worse choice if the St. Louis conference is strong.
*East Texas. Between Arkansas and Oklahoma, there are 14 D2 schools and just two D3. Being in one of those two (preferably Ozarks) looks like prime recruiting territory, but some of the East Texas schools are within 360 of Arkansas and Oklahoma AND within 70 miles of Dallas. If you're looking at an ASC job, they lose value if the University is strong, and if you're looking for a University job, it loses value if the ASC is strong. If the ASC is relatively empty, Dallas might be one of the best jobs in the game.
Obviously, as others have mentioned, there are other areas who become good or bad based on who's around them. I've had some success dipping into West Virginia as a D3 coach, but the more good teams you have in the ODAC, Freedom, Capital, Ohio, etc. conferences, the harder it is to get WV talent. If the SoCal conference is relatively empty, Chapman becomes one of the best jobs you can get.
Also, the strength of D2 conferences matters here too. Even with a strong D2 conference in the area, there will be good dropdown/pulldown options left over, but the fewer people going after the recruits, the better.
D2:
*Lewis. Depending on how full various conferences are, I think Lewis has potential to be the best D2 job in the country. There are 16 low-D1 schools in Indiana or Illinois and only seven D2 schools. Only one of those seven is within 70 miles of Chicago. This choice loses some value if the GLIAC is very strong.
*Louisiana. There are 12-low D1 schools in Louisiana and no D2 schools, which means Louisiana should be a great place for D2 schools to recruit. The closest school to New Orleans is West Florida (obviously not within 70 miles and less valuable if the Gulf South is strong), and the closest schools to the rest of the state are Southern Arkansas, Arkansas-Monticello, and Delta State.
The rest really depends on what's around you. The Virginia schools can be really good D2 jobs, but usually there are plenty of humans between the WVIAC, SAC, and CVAC who can make trouble for you. New York and California look like they could also be really good, depending on the world landscape.