What to look for in large bouquets
Ask how many stems, not how tall
Height is the number that gets advertised because it costs the least to add. What decides whether a bouquet fills a vase is the stem count and how far the material spreads at the widest point. A tall bunch of few stems stands up in a vase and shows the glass through the middle; the same height at twice the stems does not. If a listing gives height but no stem count, that is usually deliberate.
Three sizes of flower, or it reads as a bunch
An arrangement that works has something large to lead, something medium to fill, and something small and loose to break the outline — plus foliage that is a different green from the rest. A handful of identical roses tied together is a bunch of roses, which is a fine thing to buy but a different thing, and it should not cost what a built bouquet costs.
Check where the stems end
On a hand-tied piece the stems are cut to one length and bound, so the binding point and everything below it stays visible above the rim of a wide vase. Look at how that has been finished — bare wired stems tied with tape look like what they are. Ribbon, jute or a natural wrap is not decoration here, it is the part of the bouquet you will actually be looking at.