As others have noted, you might reconsider pursuing the
multi-passenger and commercial licenses.

Assuming you have the money and the question is how to spend it, you
might try:

- a few long cross-countries once you have your certificate. Can you
get your 1-passenger rating and add on night and controlled airspace?
That would be a help on cross-countries though not required. Anyway
the overnight/several-night cross-country trips are a wonderful
learning and aesthetic experience.

- get endorsements/certificates for tailwheel, acrobatic, seaplanes,
gliders, and so on.

- buy into a partnership and own part of an airplane. I own a small
two-seater and have never regretted it. Well ok for two weeks each
year during the annual I am cussing and swearing but otherwise it's
great.