I want you to get into Cymbidiums, too! They've become my most recent orchid obsession, but I'm far less knowledgeable about and experienced with them than slippers. In other words, I'm still learning. Also, I grow in a completely different climate from you and I have a different focus than yours (i.e. fragrance versus flowering size), so my experience and preferences don't directly apply to you.
Growing indoors year round under artificial lights, you probably will find a lot standard large flowered Cymbidiums challenging to flower reliably. You may need to acquire several different hybrids (or species) and experiment to see which ones do best for you in your conditions.
Do you have space to grow them outdoors from spring through fall while temperatures are above freezing? That seems to be one of the most common ways that successful "indoor" growers handle standard Cymbs.
Indoors in winter, keeping the humdity elevated is sometimes tough, especially when the outdoor air is dry and you're running heating. So, even if you get the temperatures right, don't forget to keep things humid in the grow area. The buds will drop if humidity is too low. And, the warmer the conditions, the higher that humidity needs to be to compensate.
For standard Cymbidiums, you usually want to acheive nighttime temps around 50F but below 60F (10C - 15C) to help initiate spikes, cooler is fine though. That's usually easy to do if you can leave them outdoors in the fall, may be harder if you grow indoors only. Once the spikes are set, it sounds like they're a little more tolerant of slightly warmer temperatures, but I wouldn't push it too far.
As far as what the sellers are telling you: You are correct, some of those vendors probably are telling you what you want to hear even if it's not accurate. However, there's been a lot of progress with hybridizing "standard" Cymbidiums and many modern hybrids (and even species) are easier to bloom and more temperature tolerant than ever before. Again, I'm not as knowledgeable about these things as I wish I was, so I don't know which specific hybrids or breeding lines to recommend for you and your conditions. Wish I could help there.
You may want to reach out directly to folks like Tim Culbertson and Fred Clarke to see if they have any Cymbidiums for sale that would work in your conditions. There's also Santy Orchids and Santa Barbara Orchid Estate. These are knowledgeable and reputable vendors who have a vested interest in happy customers and seem to be willing/happy to disucss things to figure out what's best for you.
As a side note: I'm finding that Cymbs are much more adaptable than their reputation might suggest. I mostly stick with hybrids that were specifically bred with warmth tolerance in mind, so it's not surprising that's been my experience. If you're willing to compromise a bit on the flower size, a lot of the commonly available warmth tolerant hybrids can be grown and bloomed indoors. These are typically hybrids that involve species like C. ensifolium from section Jensoa crossed with standard Cymbidium hybrids. One of my more recent surprises is a hybrid called C. Chen's Ruby. It's compact growing, fragrant, brightly colored, larger flowered than most of this type of breeding, and it's nicely fragrant.