Old rule of thumb...if you aren't going to develop a parcel within 6 months, don't buy it. Depending on the surroundings/location, holding vacant land long-term is risky. The local governing body can change zoning on a whim and you're stuck with an empty lot to picnic on.
I saw a listing for an ocean-view lot a few years ago in/near Monterey. $80k! What? I called the agent immediately. She told me there were water restrictions in place and the lot could not be developed for 20 yrs. Hmm...OK. That coincides with my retirement. What happens in 20 yrs., I ask...can I build then? No, she says...the water district has the right to extend the restriction for another 20 yrs.
On the other hand, I've been looking at land adjacent to an airport in a fast growing city. Nothing but empty fields as far as you can see. 20ac. parcels in the $200k range. They just lengthened the runway to accomodate passenger jets. I can imagine Avis, Hertz and National will need a lot to park their cars someday...