Learn English – Synonyms for “unfortunately”

"Of" can be alternated with possessives and adjectives. (quality of approach and variety of sentences) "This approach's quality can be improved by using sentence variation in order to enhance vocabulary and style."

Well. Here are a few that might be apt in specific situations. But remember, it is the situation and your comfort with the phrase that works best. Do not try too hard to not sound redundant. Nobody cares about too much redundancy in spoken english.

I'm definitely interested! = Count me in; You have my attention go on (from my boss)

Yeah, that sounds really interesting, I would love learning more about it! = Sounds pretty cool to me; Goodness me, is it true;

That's interesting! = Oh Cool...; That's fantastic; That's awesome

And how about these??

"I'll keep that in mind" or " I am going to make a mental note of it "