I would love to have the nemesis Romulan uniform, I'm not a fan of many of the choices we have currently.
More Parts for the Tvaro. I love the design, but I like to mix things up a little.
Romulan ship decals. The Federation has theirs, you can change it for your fleet insignia. The Klingons have theirs. I would love to have the Romulan logo appropriately placed on the head (beak ?) of my Romulan D'Deridex.
While on the subject of ship decals, I would love to be able to put the old bird of prey decal, the one you used to see on the bottom of the old style warbirds, on some of the newer designed ships. I think it would look haawwwt http://www.myspacemuseum.com/decals03a.jpg
The expand the use of ally ships to 5th tier.
Unless you buy C-store ships, the only Tier V choices for Romulan captains are the Ha'pax and it's individual parts, so why not give more options by letting you pick from Tier V allied ships too.
Missions where you get to see the REAL Romulan Star Empire.
The only real interactions we've had with the Romulan Empire up to now have been through Sela and Tal Shiar flunkies. Now that she's out of the way (for the moment) and the Tal Shiar's had it's arm broken, I'd love to see more of the state of the remaining Empire. Maybe set up a Nimbus III style adventure zone on it's capital world(can't recall what planet that is now).
Make the Vice Admiral coat a freebie instead of a veteran uniform.
It kinda pissed me off that the VA uniform for Romulans is a vet award instead of a freebie like the Fed VA jacket. Both they, and the klingons, should have a freebie uniform for getting a character all the way up to 50 too. Besides, there's already a separate Veteran uniform for Romulans, and not all of us can afford subscriptions or a lifetime package.
Stuff other people have said:
Sword of Raptor Star replica melee weapon, Raptor decal for all warbirds, Romulan Omega force rep gear, etc.
2a. Complete, exclusive and self-contained Rom Doff system. Play a Rom, use only Rom doffs and you'll see what I mean.
2b. Romulan Republic Academy.
3. Scale down the Ha'xx ships. I get that the Scimitar needs to be stupid big. The others don't and the models would look a ton better if they were smaller. Besides, there are many immersion breaking issues with the size of many Rom ships.
4. More warbirds (starting with a sci ship) that don't have a cmdr tac slot.
5. Remanland on New Romulus. What happened to that?
6. More Romulan places to go like Ganalda, K-7, Vulcan, Andoria, etc