Allen,
I have lived in Wichita Falls in 2009 knowing that when I retire form the Air Force, I would move to the DFW area. My family started house shopping and have looked all over the area. Over that time we seriously considered living in Granbury, Eagle Mountain Lake, Argyle, Flower Mound, Denton, Rockwall, McKinney, Allen, Melissa, Pottsboro, Celina, Lovejoy, Frisco, and Prosper. My wife is a teacher and we have 9 and 11 year old girls so she is very critical and concerned about the schools everywhere we look. I am an airline guy and have some flexibility where we live, which is actually a terrible deal - too many options!! Here is what we gathered on the areas you listed...
Melissa - more of a bedroom community right now with small schools and a pretty good ways out. We could not find newer houses we were looking for.
Allen - my wife's cousin and several of our friends live there and love it. The housing is pretty much built up, but they are big houses on very small lots. Wife's cousin's son just graduated from Allen High a year ago and he described it as a college. The class set up was that way too. He campus, block scheduling, very different from the high school I went to. Everything you want or need is at your fingertips and all major roadways seem to cross near Allen.
McKinney - my college roommate and several friends live there and love it. The housing is built out south of 380 but there is still new sections north. The school district lines are weird in McKinney. Some areas kids go to Prosper schools and some areas they go to Frisco and some go to McKinney. All very good school districts, but none of them are small (but not Allen big either). McKinney used to be in the sticks but now it is the outer layer of DFW, just north of Allen.
We ended up choosing Prosper and are about halfway through building a new house there. In the end it was a close tie between Prosper and Celina. Celina is just north of Prosper and still has a country feel and new construction going up. Look at DC Ranch by Emerald Homes if you are set on half acre or more lot in a neighborhood - it is right near the high school and Celina and was a contender for us. Celina ISD gets great reviews but is a little small. They have awesome basic sports teams, but very little academic and other sport (like swimming, volleyball, etc) opportunity. Eventually Celina will be the new Prosper (15-20 years tops).
We really like what we have seen in Prosper. The ISD gets great reviews and the high school is big, but only 1/4 full right now. They have planned for expansion. They also have a good plan for building more schools as required and they are even holding off on a sports stadium until they can pretty much pay straight up for it (novel concept in this credit driven world). The location is nice because it is just north of the end of the Tollway and 380 so if you go South, you have Frisco and all it offers, East is McKinney, North is farmland and Celina. SO basically it is currently the edge of North Dallas Area build up but they already have plans to build further and Prosper will eventually be the next Frisco. Thats not a bad thing at all, just reality. Currently Prosper has a nice small feel and everything in the public works is super nice, the PD, FD, city park, etc. To be frank, there is tons of money here and it shows. You will not find a 1/2 acre lot in a neighborhood unless you are in the 650k+ price range. The median home cost is around 425k. The plus side is you will get a big house, and most of the neighborhoods have one or more pools, parks, playgrounds, etc. The city park, Frontier Park, is really nice too. Prosper is 45 minutes from Lake Texoma (that is where we have our condo and boat), 20-30 minutes from Ray Roberts and Lewisville, and 45 minutes from Love Field.
One other place to consider if you want to be more South and East is Lovejoy. The ISD there gets rave reviews and the high school is not gigantic. The homes are older but there are some big lots still that direction.
Realize that DFW is BIG! The school districts are generally very good, but they are not small. You have to go out a decent ways to get small schools but then you sacrifice the opportunities that the bigger schools can afford to do (property taxes are about 2-2.5% most places). If you have dreams of star athletes in the major sports, then they better be above average to play in the big districts. I view these schools as opportunities for academic and extra curricular broadening for my kids. Playing multi-sports and doing different academic things just isn't possible like it was when I was a kid. Most folks seem to latch onto a sport and try to make their kid an Olympian or Professional caliber prospect at a young age. You just have to decide what you want for your kids and what you can afford to make that happen.
Probably more info than you wanted/needed. I will be happy to answer any questions best I can!