I am frequently asked for houseplants for a sunny windowsill and I have to say that not many fit into that category very well. Hibiscus rosa-sinensis (Rose of China) however actually requires bright light in which to thrive so is one plant I can recommend.
Indoor hibiscus have dark green glossy leaves and large showy flowers which come in red, pink, yellow and white varieties. Look out for the double-flowered types as they are particularly flamboyant. Many people are put off buying hibiscus because the blooms only last for two or three days but the plant more than makes up for this by starting its flowering season in early spring and continuing well into the autumn, so there is a constant succession of flowers opening up throughout summer.
Hibiscus are shrubby plants which, if left unchecked, will grow to 4 ft. or more, which is fine if you have the space to allow them to develop. The best way to keep them under control is to prune the branches back by about 1/3 in late winter, removing any dead growths to leave an evenly shaped structure. Prune each branch just above a healthy growth and the plant will branch out from that point so creating a nice bushy plant.
Two important points to remember with hibiscus are to keep the compost moist and to mist-spray the foliage regularly as dry air will cause the leaves to curl up. Just make sure the pot is not left standing in any residual water in its saucer or pot cover as this will cause the roots to rot if left for too long.
Aphids can sometimes attack the developing flower buds so keep a regular check on those and use a systemic insecticide at the first sign of any problems.
Re-potting should only be required every couple of years or so, at the same time that you do your pruning.