Your itinery sound pretty good!
I love Innsbruck, the location is really beautigul, right between very high mountains. You will have stunning views.
The hotel Iike best is the Penz Hotel - I wrote a review:
http://www.tripadvisor.com/Hotel_Review-g190445-d237821-Reviews-The_Penz_Hotel-Innsbruck_Tirol_Austrian_Alps.html
I really like sitting on this hotels terrace cafe/bar and watch the sunset with this awesome view of the mountains!
The Hilton is good, too.
When going from Salzburg to Vienna you could make a sidetrip to the famous Salzkammergut with its beautiful lakes, mountains and small villages:
http://www.salzkammergut.at/
I like the lakes Traunsee, Attersee, Wolfgangsee and Hallstattersee.
And the villages Gmunden, Hallstatt and St. Wolfgang.
There is a really nice hotel in St. Wolfgang - the Landhaus zu Appesbach:
http://www.tripadvisor.com/Hotel_Review-g296672-d315688-Reviews-Landhaus_Zu_Appesbach-St_Wolfgang_Upper_Austria.html
http://www.tiscover.at/at/guide/5,en,SCH1/objectId,ACC110361at,season,at1/home.html
http://www.schlosshotels.co.at/index.php?l=e&s1=hotel&s2=hotel&id=2