I think that the beasts are some of the best aspects of the 3 3/4" line, and also some of the most neglected--or at least difficult to come by.
We've been given a new Jabba, a new Wampa, and a new Han's Tauntaun. I would like to see the Eopie with Qui-Gon reissued for a start. I never saw this in stores, and no no one who did. It was immediately priced at over $50.00 on the secondary market and now goes for around $150. This is way too much for a $15 set that should have been more readily available.
Beyond that, there are a number of beasts, animals, whatever you prefer to call them, that haven't been made yet, and some variants that could be made as well.
Here are what I came up with:
The Sarlacc - A Sarlacc pit playset would be a great addition to the line.
The Krayt Dragon - Though only seen as a skeleton in the movie, who wouldn't want one of these?
Jerba - This pack animal seen outside the cantina and Toshi station in the deleted scenes would be great with a generic moisture farmer.
Shaak- They do look like big ticks, and some people hate them, but I still want one.
Ikopi - Mainly seen running in the Naboo swamp, but interesting looking.
Kaadu with the decorative feathers - with Captain Tarpals.
Blurrg - These are those big mouthed dinosaur things from the Ewok movies. Great looking monsters, and I don't think that anyone would reject them based on the source material.
Dianoga - I haven't opened my Trash Compactor sets so I don't know how that dianoga looks assembled, but a complete one on its own would be nice and we don't need another trash compactor Luke either.
Orray- with a Picador from AOTC.
Aiwha - with Kaminoan rider.
Dewback - as a beast of burden like the one that passes behind Qui-Gon and Padme in Mos Espa.
Gardulla the Hutt - This is at the top of my list.
Colo Claw Fish - This would be great.
Dragonsnake- Only seen as a hump in the water before it tries eating R2 on Dagobah, but a great monster nonetheless.
Sando Aqua Monster - A problem with scale comes into this, but I'd take a smaller scale version if necessary.
Giant Space Slug- Same with this one.
Scurriers/ Dwarf Nunas - as a pack in with other figures, or as an accessory set of their own.
These are the ones that received screen time in the movies. There are a number of EU choices as well. "The Wildlife of SW" book has a lot of additional great choices.