I would not apply the term "up & coming" to an area that has been in demand for decades. The fact is that tastes / needs in housing drive the tear-downs in desirable areas, not any 'gentrification' trends where undesirable elements need to moved out
Crime is a non-issue and the resale value of homes anywhere in DuPage Co within walking distance of the BNSF or UP-West is quite solid-- for families the area is hard to beat. College Ave station in particular has several expresses under 40 minutes.
http://metrarail.com/content/metra/e...20Schedule.pdf
It would only be a little risky to buy a brand new house that is much larger than the average on a block in that desirable section of Wheaton, simply because the current likelihood of the smaller houses being upgraded / torn down is nowhere near as high as it was a few years back. But that does not mean that the older homes are ever really going to go "down hill" and those are not really your competition either.
The competition might be other houses elsewhere in town that might be slightly newer or more upgraded than yours at the time you may want to sell and that is so hard to predict as to be impossible.
The older smaller house might carry a lighter tax burden, but that too is something that ought not to be too big a concern, as there is some offset in having a house that probably is more efficient and won't need as much maintenance.
I might be a little reluctant to fall in love with a $1M in Wheaton unless I had also throughly evaluated what that would buy in towns with an even greater 'desirability' factor. In town Glen Ellyn & Elmhurst ought to be evaluated, as well as similar sections of the in-town areas further west in Geneva, and of course you would be wise to at least give serious consideration to the similarly developed sections of Naperville, Downers Grove, Hinsdale, Clarendon Hills, Western Springs, LaGrange and maybe even Riverside along the BNSF.
The truth is that if you have lots to spend the variety of housing has never been more varied.
Some of the folks that grew up in a specific town and now have the income to put a "house of their dreams" on even the same lot where they were a kid is one aspect that draws people back.