I think lilac trees are boring for 11 months of the year but for a powerful scent they are hard to beat in late May.

The White Lilac is every bit as scented as the ‘lilac’ Lilac.

For tips growing Lilac see this post

For cut flowers

• Pick stems early in the morning when full of sap.
• Put immediately into warm water,
• Split the stem for 1″ with a sharp knife do not crush.
• In this way they should last more than 4 days but otherwise Lilac will disappoint.

There are many varieties of Syringia of which the common lilac Syringia vulgaris is best known (see below).
I particularly like the smaller better behaved Syringia microphylla Superba above as a garden shrub or small tree.