I believe Sansiveiria would be fine there. I'm not 100% sure of their cold tolerance, but I believe that's acceptable.

Sansevierias might suffer a bit below 50 deg.

Best bet would be Yucca in the sunny bits.

Kentia palm would probably take that temp range in the shade.

Hanging plants - ivy is the only option that pops in to my head but might get v crispy in the heat!

Shady...Fatsia japonica, Aspidistra, some of the large leaf philodendrons like Split-leaf, Aucuba, Xmas cacti, Azaleas, Camellia.

Sunny....Oleander, Pittosporum, Podocarpus, Chlorophytum, Citrus, Bamboo varieties.

I know I'm missing a slew of possibilities, but all of those will do well for you in an indoor solarium...which will be fairly humid, I am presuming. The cooler temperatures are a real plus.

My Mom does similar with her garage. It has 2 big windows and doesn't freeze. I have another friend with an unheated porch and she staples sheet plastic around the openings so her plants can stay out there for winter. Between the two, they've kept Dracaena fragrans, plain green spider plants, majesty palms, Callisia fragrans, Tradescantia zebrina, heart-leaf Philodendron, cane Begonia, Persian shield, Boston fern.

I would also be confident about Gardenia, Daphne, Crape myrtle, Azaleas, Hibiscus, Rosemary, many Begonias, some of the Jasmines, Bougainvillea. How much sun are talking about in the sunnier spots? Direction, length of exposure?

A lot (most, all?) of the Tradescantias are herbaceous perennials and would come back even if they went dormant, T. zebrina, pallida. Same with Callisia repens, Gibasis geniculata (Tahitian bridal veil,) sweet potato vine, Syngonium, spider plants (at least the plain green one.) Those are all back from last year, in the ground (and some in pots) outside all winter, as did Persian shield.

Then there's bulbs and tubers... Caladium, Dahlia, Cannas, Calla lily, elephant ears (Colocasia,) Oxalis, Amaryllis, Lycoris radiata, Cyclamen, daffs, and any that don't need a prolonged chill.

The more I think about it, there's really endless possibilities. My only problem would be prioritizing the really sunny spots and spending too much time lurking the Florida forum. Just remember in general that the cooler the temps, the less you'll need/want to water.

Some of the more cold-tolerant palm species would do fine under those conditions -- Mexican and California Fan palms, Chinese Fan Palm, European Fan Palm, Windmill Palm, Jelly Palm (Butia captitata), Serenoa repens, Needle Palm, all of the subtropical species of Sabal.

It depends a lot on how sustained those periods of cold are. I am assuming you can ventilate it somewhat in the summer to help keep the heat down to some extent. I have had experience with gardening in a small, 'Three Seasons' or 'Florida Room' that had to endure a 'cold' winter range of 50-70 F., and currently overwinter many subtropicals in a large, very sunny, loft, cold garage with an extreme range range of 32-70, but tends to be in the 50's or 40's during very cold periods. Here's what does well for me-- (asterisk, *, means I grow them outside in ground so should work protected for you)

Phoenix date palms (most are much too sharp/dangerous for inside a living area, Roebellini is least injurious but will resent it if cold duration is excessive)
Pindos palms
Queen palms
Most Sabal palms
Livistona chinensis (Chinese fan palms)
*Mediterranean fan palms (Chamaerops humilis)
Cycads revolution and a few other cycads that seem cold tolerant (Dioon, some Encephalartos)
Yucca elephantipes
*Podocarpus
*Aspidistra
Gardenias
*Basjoo banana
Schefflera Arbolicola
*Many species of bamboo
Guava
*Fruiting fig tree
Even my Caribbean avocado made it last winter
*Camellia and Acuba japonica (here sold as outdoor shrubs)
*Windmill palms
Citrus (esp. Kumquats or calamondins)
Oleanders
Araucaria
Agave
*Rosemary
*Pomegranate
*Loquate
*Lemon verbena
Cordyline indivisa (Dracaena spikes)
Radermachera (China Doll)
*Magnolia grandiflora 'little gem'
*Hedera canariensis
Osmanthus fragrans (sweet olive)
*Jasmine (confederate jasmine is nice)
*Bay laurel
Asparagus fern
Some tree ferns

Good luck!

thank you for all the input I will try several of these and see how they do.

Wow! That's part of your house? If you tell me there's a drain in the floor, I'm moving in, scoot over. I think I will dream about this structure tonight. Sweet!

Dan, my dream house! Wow..

Succulents will do well inside your sun-house....Toni

Maybe you can take some of mine! Oh, forgot the Cali. and Mexican fan palms that are so easy.