Question: Can't seem to find the definitive answer to this. What restrictions should I look out for between the two? I currently use foursquare exclusively, but sometimes there are places not in foursquare that maybe I want to use Google for.

**Update**

I use the 4sq API only for the name of the place and lat/lng. I don't want to use a combination of 4sq venue data, and Google Places data, for the same place... just want to be able to check both services to pull name/location data.

Answer: 
<https://developer.foursquare.com/overview/community> explicitly says

"Venues Database Usage
...
DON'T perform a search across both foursquare and Google Places, then return a combination of their results/data."
In the "Venue database usage" Foursquare policy seems to accept a combined use of their API with others as long as the rule of attribution is addressed:

"You can show information from these kinds of sources side by side, so long as the data from Foursquare is in its original form and clearly attributed to us. As a rule of thumb, a user should be able to point to any piece of data on the screen and clearly be able to say “Oh, this is from Foursquare” or “Oh, this is from Google.”

However it would be wise to check also what Google say about this.