I also found a model of a Piper Cherokee but again don't know if that would be found at a small airport today?
Almost certainly. After the Cessna 172 & 182 models, the Cherokee is one of the most common small aircraft going.
Generally, aircraft last longer than cars. The vast majority of small private aircraft out there are going to date from the 1970s or earlier. There was a real drop in production in the 1980s, for a variety of boring reasons, then production started to climb slowly in the mid 90s. So anything that looks fairly modern could well be spotted on the apron of a small airport.
Also what type of modern military helicopter would the National Guard be using today? Or the Marines?
The Blackhawk seems to be ubiquitious with the US military these days; a quick google shows a number of people make a 1:48 diecast one.