Need a nice flower or shrub recommendations please?

its for a small border that has full sun.

Hibiscus Shrubs come in lovely colours and don't grow too quickly. They keep their shape better than some Shrubs. You could plant bulbs as well. It's nice to see dwarf daffodils and Narcissus in the Spring. Leave them in after flowering.

Does Hibiscus require much watering or attention during the summer.

About 2 minutes continuous watering every day from a sprinkler

I wouldn't say they need a lot of watering once they are established.

That's not a lot of water from an irrigation sprinkler maybe 2 cup fulls

I have quite a few mature Hibiscus and they very rarely get watered. In pots they probably would need more but planted in the ground they seem happy enough.

I like Oleander, they require very little care and water, come in several colours and can be pruned back hard in the Spring.

With Hibiscus it's essential not to stress them, by watering them, not watering them, feeding them, not feeding them... Anything out of the usual causes them to drop their buds before flowering, get it right and they are glorious

I inherited a hibiscus when I bought the apartment and it has survived the last 2 years without any watering other than when it rains and still produces lovely flowers. It is a well established, mature plant though.