You are so sweet to want to have the best for your gerbils! Do you already have toys in their home for them, like toilet paper rolls, small cardboard boxes (they love to chew!) and a safe exercise wheel? My gerbils just love to come out of their home and run back and forth on my lap as I sit in a chair, or just carry them around the living room with one of them perched on my crossed arms, so they can look at things and have a ride. We also put a towel down in the bottom of our bathtub, then set out a few little toys/boxes and let our two gerbils run around in the tub for about 15 or 20 minutes. They love to run and stretch their legs! And I swear they love to hear me talk to them in baby talk, ha ha.
Hope some of that helped!
(p.s. they love Roll-A-Nests from Petco, or a handful of timothy hay in their tank. And they LOVE a bit of banana or cheerio as a treat!