Because you are staying in a roomette you classify as "first class" passengers so you will have access to the "CLUB ACELA" at New York Penn Station, its a nicer place to wait then in the other areas of the Station.

Once you get outside the Northeast Corridor (NEC, Bos-Was) timeliness all depends on how generous the frieght railroads are (since south of Washington, DC all amtrak trains travel on frieght owned tracks). Last figure I saw was that the SilverService had a 22.5% on time performance, not so great, so if time is not an issue, I would also give some extra time padding for your Tampa arrival.

I hope this information is helpful, i'm sure others might be more insightful, and that you have an enjoyable trip.