I won't be dealing with a huge dimensional matrices, but maybe around 30 by 30 and up to 70 by 70

but I need to find eigenpairs of a laplacian matrix which is symmetric and 'somewhat' sparse.

Would Eigen be suitable for that?

For such small matrices simply use a dense MatrixXd and the SelfAdjointEigenSolver. Even for a 1000x1000 matrix, it will take less than a second.