I am trying to plan on a second language to learn after Romanian. I want it to be something useful (spoken a lot) but also quite similar to Romanian, so that I can make connections.
Any suggestions would be greatly appreciated!
I haven't done enough Romanian to be sure, but I think it's more that Romanian is a Romance language that has grammar closer to Latin than the other Romance languages and has some influences (and vocab?) from Slavic languages. I don't think it's particularly Slavic in grammar.
(IIRC it does share some features with the Slavic languages of the region, including some Slavic ones, from neighbouring countries, as part of the Balkan sprachbund, but that is a long way from saying it has Slavic grammar. After all, it also includes, afaik, Greek and Albanian, not just Slavic languages.