As someone kind of partial to these old favorites, here's a few exciting varieties worth taking a second look at:
Syringa vulgaris or Common Lilac: The straight species of this in renouned for its intensely fragrant flowers, and great lilac spring color. But, it is also scraggly, prone to mildews and diseases, and confusing when it comes to pruning. Cultivars such as 'Little Boy Blue' (blue) and 'Prarie Petite' (pink) have a more compact habit which makes it more versatile in the landscape. 'Prince Wokonsky' has double flowers, and 'Elsa Maasik' (deep purple) is more disease resistant than the straight species. 'Albert F. Holden' is bicolor.
Chaenomeles speciosa or Common Floweringquince: This may be dismissed as too scraggly or wild, but the flower show is what really makes planting a Floweringquince worth it. Going from there, lots of different flowering varieties have been released covering the gamete between white and dark red. 'Jet Trail' (white), 'Minerva' (red), and 'Texas Scarlet' (red) are a few of the more compact varieties if the Floweringquince's legginess is too much for you. 'Scarff's Red' is a thornless variety available, although the thorns may come in handy for a barrier or hedge.
Spirea prunifolia or Bridalwreath Spirea: ... Ok that one may not have any hot new varities, but take a look at it at this time of year. Its one of the greatest for full white spring flowering, and attracts tons of wildlife including honeybees and ladybugs (both of which are necessities for any healthy garden). And the rest of the year, it makes a nice green mounded background for your summer and fall flowering colors.
Sources:
Dirr, Michael A. Manual of Woody Landscape Plants. 215-216, 962-963, 986-991
Common Lilac picture 'Albert F. Holden' from http://www.naturehills.com/images/productImages/SyrvulgAlbertFHoldenLilacviolet_big.jpg
Floweringquince picture 'Texas Scarlet' from http://www.jparkers.co.uk/images/new_products/ST0403.JPG
Bridalwreath Spirea picture from http://www.donnan.com/images/SpireaBridalWreath.jpg