The larger tulips are less likely to naturalize. Planting them at maximum depth may help. You can always put groups of them in with your other bulbs for a very showy effect even though they may not be long-lived. There are other dramatic less common large Fritillarias available. Try F. Persica with plum colored flowers, first introduced in Turkety in 1753.
Foliage looks good most of summer.
Flowering period is usually short. MUST have good drainage. Have grass-like foliage that forms dense clumps. Need two to three years to become established. Don't judge by first year's bloom.