1. 'It was a longer trip for me than I’ve taken in the last couple of years.'

2. 'It was a longer trip for me than I had taken the previous couple of years.'

I think in the second sentence 'those' must be there after 'than' to make it grammatically correct. Am I right?

In the first sentence, "is" in place of "was" would make it correct, but both past and present are used; that's why I am confused.

Another thing I would like to point out is 'had' in place of 'taken' would make it more natural.