Combining multiple passes

Hi! We will stay 15 days in Japan this summer. We will be in Tokyo for 7 days and travel Northern Honshu for the remaining 8 days. We fly in and out from Narita (NRT). Now we are wondering what the right rail pass(es) for us are. The most comfortable way is probably to get the full rail pass for 14 days, and cover the remaining day with a day ticket. However, I guess that would be kind of a waste if we will only be in Tokyo for the first week. Do you see any other combinations, e.g. getting a 1-week-pass and combining it with other tickets? Thanks!