I agree with Mark. The IFR alternate is entirely a fuel-planning issue. The alternate really has no other purpose than to enter into the fuel computation. If you can't get to the destination+alternate+45, you've got a problem as far as the regs go.
As for me, not only do I want a LEGAL alternate, I want one that will likely work AS an alternate. If I fly to my home field NC26, I always need an alternate as it has no approach. Legally, I could file SVH (5 miles away) as the alternate, but if the weather is bad one place, its likely just as bad 5 miles away.
If I had filed SVH as my destination, the nearest alternate would be 20 miles away. So if I file to an airport without an approach I by regs need 5 gallons less fuel than if I file to one with an ILS.