Around here, BDR and HVN are about 10 miles apart, both right on the
edge of the water. What's happening at one weather-wise is pretty
much guaranteed to be happening at the other. Yet, it's perfectly
legal for me to file IFR to one and use the other as my alternate.
Legal, but pointless.

When I'm picking an alternate, my goal is to find someplace that I'm
damned sure I can get into if my destination goes down. That implies
a much more conservative approach than just meeting the letter of the
law.

Sometimes I encounter the opposite problem - there's no real danger of being
left without a safe place to go, but it's hard to find a legal alternate
within range. This can happen in the summer when there's a slight chance of
thunderstorms over a large area. All the forecasts include something like
"TEMPO ceiling 500, visibility 1 in heavy rain showers," making them
unavailable as alternates, but since the storms are only scattered, there's
very little chance that all the airports will be unusable at the same time.