Wanted to run some ideas at you all..

This won't guarantee I'll pick one over another, but I wanted to see what you're interested in. You can even pick multiple ideas you like!
(To note there are a few others  in the  "Hey why is that not on the list", I'm just  waiting on voices for those. Not anyone's fault, just busy times :D )

1. [Character]* bragging about how good and big/unpoppable she is as she grows compared to someone else, something on her is actually able to pop as she grows to huge sizes. Voiced. (See below for character info)

2. Bremerton + FDG (yes: that one of them on the park bench) but super extended and Friedrich blows up Bremerton and a couple other hijinx ensue. Voiced also.

3. Lindsey finds that the POV (you) have a inflatable doll of Lindsey herself. So she blows her up via pump and valves (this is a render sequence but I liked the concept a lot) (Voiced)

4. Hassan of Serenity + POV. Her kiss causes you to inflate now since you're immune to poison. She tries to inhale from the POV but it goes out of control. (Voiced)

5. DVa gets an advertisement on her butt for Lindsey, but due to contract regulations, it's completely not visible enough, so the clear course of action is to inflate her butt to show it off bigger to viewers. (Possibly voiced)

6. Tamamo Fox and Cat again -> Fox is showing Cat how to inflate a bubble of herself. Using a full body setup.  ( similar to a hybrid of the old Miku+Lindsey one I did with the body shape and the Pink Lindsey one). I have a cute story for this that I was sitting on for a while and I realized that Fox and Cat would be perfect for this. (No voice/low chance of voice)

I do have more ideas but I just wanted to present a few here for fun that I had going around to get a bit of feedback.

[Character]* - From the first base idea was for Karin from Street Fighter. But this can fit for a lot of characters really. WITH Karin the second character could be Sakura or R.Mika. (Quick edit for clarity) 

EDIT: It could be another character I'm just seeing who would work well. I'd love to try Karin but in case she's not available or the model isn't working right I'll have other options.