I agree with gruezi - the Jungfrau Region is the absolute highlight of Switzerland - not that other areas are not fantastic but this area, with so many varied things to do - is even more fantastic. If you have to select one place to stay a few days or weeks this for most visitors would be their favorite IMO

If you try a day trip to Jungfrau, you might want to pack a few little overnight supplies in your day bag just in case you find a nice little place to overnight. You might get a great walk in rate. Couldn't hurt, and it shouldn't break the bank.