I would vote for getting to Anchorage right away and renting a car. Maybe you'll find a congenial couple to split the cost if there's only 2 of you. The scenery going to Anchorage is stupendous. You might want to drive back along the Seward Hwy for some photo ops with a visit to Alyeska, ride up the tram and a little hiking.
Or head north from Anchorage to Independence Mine. Since you've been on a cruise, this would be very different and give you an idea of what it might have been like to live in a remote town way back then. Some buildings have been restored. The scenery is nice. You can do a little hiking. It's a short, easy hike to the mine entrance.
If you decide to stay in Anchorage, we enjoyed the trolley tour. It wasn't that long. Get out to Lake Hood where the sea planes are parked.

I would consider going out on a Kenai Fjords boat before leaving Seward (IMO, well worth it, especially on a nice weather day), then possibly renting a car and heading for Anchorage, perhaps stopping at Alyeska and or Portage Glacier. Note: Expect some steep fees for the one way car rental, but you have time to try to find the best price.

Kenai Fjords is awesome.

Another option is Alyeska/Girdwood. You can hike at the top there via the Gondla/tram. Also at the bottom of the mountain is the Winner Creek Hike there is a good option. The hike involves a self pulled trolly thingamajig that you pull yourself over the creek with. Very cool! They have a ton of other options like tandem hang gliding etc.

Riding the train back from Seward to Anchorage is great too.

Yet another option at Seward is hiking to Exit Glacier.

If money isn't an object, then perhaps a half day Fishing excursion from Anchorage.

Thanks defrostnh, hpeabody, and spirobulldog.

We really don't want to rent a car, so that is not an option. It limits most of the other options that you all suggest as well, but thank you for those anyhow. We want to leave the driving around to a guide, but don't want to spend a fortune. We may be asking too much!

We seriously thought about the train, having read about the views and it sounds great. But the train doesn't leave Seward until 6 PM. Our third and maybe best option is an 8 hour day tour. And I believe I found one that might work. Anyone hear of or use the company is called "Shoretrips"? It would tour the area and end about 5 PM in Anchorage. We'd drop the luggage at the airport (or keep it with us) and go into town on our own for a meal. Given our parameters is this our best day option?

I like the trolley tour idea, so if it is running in the evening hours, it would be a perfect fit. Any restaurant suggestions for an evening meal downtown Anchorage?

Restaurant suggestion: Orso on W. 5th.

downtownbrown, Orso looks very inviting, and reviews on tripadvisor are all excellent. Everyone loves it. I'm always a bit wary when no prices are given on the menu, however. We are tempted to try it, in any case. Thank you.

Before you leave Seward, some nice attractions that are not very spendy are the Sealife Center, Ididaride Sled Dog Kennel, and Exit Glacier (there is a shuttle from Seward to Exit Glacier for $10 per person).

For a guided tour from Seward to Anchorage you can check www.akcruiseshuttle.com or akcruiseconnect.com. These are guided tours that can include photo stops and attractions like the Alaska Wildlife Conservation Center, Alyeska Resort Tram in Girdwood, and Potter's Marsh.

Yes, Orso is a pricy restaurant but good. My favorite recommendations for restaurants in Anchorage are Moose's Tooth and the Sourdough Mining Company, however, these are not downtown. My favorite downtown restaurant is the Glacier Brewhouse.

You might want to check on a dog sled ride in Seward: http://www.ididaride.com/ It is given year round by Mitch Seavey who won one of the Ididerod's We really enjoyed being there.

I'd strongly agree with the suggestions of the Kenai Fjords boat tour. We took one of thoe to the Aialak Glacier just after a cruise, and the day tour on Kenai Fjords was way, way more interesting than anything we'd seen on the 7-day cruise.

We took the train to Anchorage, which was actually a lot of fun, especially when a bear decided to run along with the train for a few hundred yards.

Jason- Thanks for the links for transportation/tour from Seward to Anchorage. The second link is promising as there are a couple of options I'm going to check out.

The restaurant will probably be a last minute decision. Both choices sound good so it might come down to what we feel like at the time.

cd- Though I'm not much for dog sleds, thanks anyway for the suggestion.

Don- I do think that a tour that gets near or into the Kenai Fjords is what we'd like before heading to Anchorage. Thanks also for the tip on the train. But, it leaves early evening from Seward and gets into Anchorage at 10 or so. That is time enough for us to take it, but leaves no time for Anchorage itself. Thus we are leaning away from that option.