Rosefolly, welcome to Rocky Mountain Gardening. Someone will come along with more lilac knowledge than me. If you do end up moving here watch for the spring swap. There is often a lilac or two there.

Based on the original owners plant list I believe we have Sensation Lilac. It is your basic purple lilac and has a lovely scent. It gets really big. We ended up taking it out due to the drip head that fed it broke and drowned it. But it sprang up (we believe) in another location where it is still growing. However even there it is now too big and taking out just the big canes makes it look awful. We haven't mastered how to trim these big ones successfully.

https://www.monrovia.com/sensation-lilac.html

We also have Beauty of Moscow. It grew really huge and we decided to tame it by digging it mostly out and leaving one of the off shoots. It still lives but never recovered. However, I thought it was a wonderful plant. It just was too big for where we had it.

https://www.easytogrowbulbs.com/products/lilac-beauty-of-moscow?variant=40767573950575

Both of the above get really leggy. We tried following the advice on how to trim them but they just ended up looking awful and were absolutely huge. They were on the edge of a sunken courtyard and made it feel like a well so we took them down/out.

Our third is Dwarf Korean. I really like this lilac as it is a nice bush form, easily shaped and has wonderful blooms. But this is probably the one you didn't care for the scent. I like it but it isn't the same as the big bushes. We've even dug up some of the sprouts for the swap and transplanted one to the front of our house where it continues to delight. This plant can be as big or small as you want to let it grow and takes a trimming really well. It just comes back thicker. Have to only trim after the flowers as the new growth sets the flowers for the following year so if you trim in the fall it will affect the flowers for the next year. Makes a really great thick hedge with regular trimming.

https://www.arborvalleynursery.com/plants/dwarf-korean-lilac

Dwarf Korean blooms after the other two. Maybe try different types with different times of blooming to get more lilac scent longer.

Syringa microphylla

It doesn't have exactly the same scent as S. vulgaris, but it isn't the privet smell of the Koreans and their hybrids. It's supposed to be a bit fussy, so it may not like Colorado. It definitely likes here.

There are early, midseason, and late varieties of S. vulgaris. They do tend to be lanky, awkward shrubs. Mine are particularly bad since they are in the shade of a large oak.

Lilacs will grow anywhere that has a reasonably cold winter. And the ones with the most intense fragrance are selections of Syringa vulgaris or common lilac (species and cultivars).

I am skeptical of any extended bloom time with these. These are traditionally May bloomers, some in early May and others slightly later but for only about 2-3 weeks max and then done for the season.

Common lilacs are caning shrubs and therefor easy to keep under control. Once well established, each year remove no more than one third of the oldest stems. This will rejuvenate the plant and keep size in check. Alternately, since these flower on wood produced the previous year, you can prune to size immediately after flowering.

Full sun, neutral soils and chilly winters.

btw, 'Sensation' is a raspberry purple bicolor with a thin white border around each individual flower. Quite distinctive and a good bloomer. And with a strong fragrance.

Based on Gardengal48's description I think we killed our Sensation and we had a common purple lilac grow in another spot. Most likely as seed dropped by a bird. I do have fond memories of how good the Sensation smelled.

Look at 'Yankee Doodle' I believe it's a Father Fiala lilac and was bred not to sucker. The deep rich purple and the scent are wonderful.

I have 3 lilac bushes in my yard. No idea what variety. They have been there 25 years! I often bring their babies to the spring swap! Who wants one this year?!?

i have over dozen varieties on site. grows well here. I prefer to start smaller plant unless I have trouble buying the variety I wanted , 5gal pots do work slower then smaller plants and even out in 3 years

Good to know that I can start with a smaller plant and it will catch up in three years. Thanks for that.

I have in the past grown 'Sensation' and it is a favorite of mine. Currently I am living in a warm winter climate where we have to grow the Descanso hybrids or Ralph Moore's 'Blue Skies', lilacs bred to bloom without much winter chill. Their fragrance varies, but none of them match the Syringa vulgaris scent. 'Sensation' however, does have the right fragrance, so I am happy to learn that it does well in Colorado. I would still like to find another lilac that blooms either a bit before or a bit after it to extend the season.

I do so love lilacs.