There are a lot of things to like about Padua.  It is easy to get to from either Venice, Milan, or Florence by train.  It's really not too bad to get to from Rome either.   The hotels I like in Padua are the Hotel Belludi 37 and the Majestic Toscanelli.  Alternatives are the Albergo Verdi and despite the small bathrooms, Hotel M17 is a good value.  Get a hotel in the historic downtown area (like the ones mentioned) instead of staying in the business district.   All of these hotels are a good value.

Padua is compact and very walkable.  I enjoy walking around one of the four squares and visiting the various markets.  The produce market is the most colorful and enjoyable in Italy.  I'll stop in for a cafe at the grand Cafe Pedrocchi, visit the Duomo, and walk through the charming Jewish Ghetto.

Other sites to see on a visit to Padua are:

Scrovegni Chapel: The superstar of Padua.  Giotti's frescoes, in my opinion, are more amazing than the Sistine Chapel.  Worth the trip to Padua alone.  It certainly has more historical significance than the Sistine Chapel.

The Churches:  The most famous is "Il Santo" or Basilica di Sant'Antonio da Padova.  Pilgrims come in awe to touch the resting place of Saint Anthony (yes, THAT St. Anthony) and pray in this marbled church.

Cafe Pedrocchi:  This neoclassical style is rich in marble, open ceilings, and the perfect place to sit to watch the world go by.

Palazzo Ragione:  Outside of the vegetable market, the largest roof in all of Europe.  The massive inside space adorned with frescoes is a work of art.

University of Padua:  During its time, it was probably the intellectual center of the universe.  Galileo spent his best years there.   See his lectern and other fascinating sites on the tour.

There are also examples of architecture, good art museums, and botanical gardens to spend time at.  Compared to the big tourist cities of Italy, Padua is much more laid back (and less expensive) and is a terrific trip for your 2nd or 3rd time to Italy.