Sacramento is one of my favorite cities to walk around.
My favorite HI hostel is at the intersection of 10th & H across from City Hall. The River City suite is on the first floor and there are several other private rooms on the second floor.
Things to see in Sacramento include Old Town Sacramento including the California Railroad Museum and the Capitol grounds. I don't know if you can still get inside the Capitol. From the balcony over the rotunda you can see the state motto on the floor "Eureka".

Don't know your budget, but I would stay at Le Rivage or Embassy suites on the river. Le Rivage is further down the river so you would need to drive to the old town. Embassy Suites and also the Delta King river boat hotel are right in Old Sacramento.

Lots to do in Sacramento and several nice properties. What is your budget?

Must you stay in Redding? It isn't very nice and even in June can be hellhole hot. Maybe for one night to base for Lassen. But for Mt Shasta/etc I'd stay in Mt Shasta City, Dunsmuir or McCloud.

We've stayed at both the Sheraton in downtown Sacrament and also the Residence Inn in nearby Natomas, I like the Residence Inn you get free full hot breakfast and light dinners M-Th.
We visited Old Town, Railroad Museum, American River parkway and took a cruise (on a friend's boat) on the river but we were there either on business or to visit relatives.

I agree with Janis regarding Redding.

I like staying at the Residence Inn Capitol at 15th & L. Spacious rooms, reasonably priced, and easy to walk around mid-town and downtown.

It is right in the thick of things, but in what I think is a really nice area of Sacramento. You can take a tour of the Capitol (highly recommended!). Take one of 2 buses that run along L (I think the 30 and the 42B) that will take you down to 5th, then walk through the mall, under the tunnel to Old Sacramento (about 5 minutes from where you get off the bus). There's a lot to see (and places to eat) in Old Sacramento, but the Railroad Museum is spectacular, I totally agree.

Lots of cute bars and restaurants really close by the hotel too, from Rock Pizza, to Zocalos, Paesanos, to De Vere's Pub (right around the corner) to our new favorite restaurant, Lucca. Our last trip 2 weeks ago, we had a nice meal further up mid-town called Red Rabbit on J Street.

Hi folks. Many thanks for the information.
It gives me a good starting point from which to plan the holiday. Previously I knew nothing of Sacramento.
It's very much appreciated.
David

Old Sacramento is very nice. As for Redding, please go North to McCloud or Mt. Shasta City, you will be so happy you did!