Giving 'get well' flowers as an encouragement and symbol of a warming, sympathetic thought is a nice idea and often much appreciated. Colors, scents and textures of get well flowers can all communicate a message of sympathy you want to convey to a dear friend, family member or such.
If you are sending 'get well' flowers to someone you know quite well it may be a nice touch to send them their favorite flower or flowers in their favorite color or maybe even see if the florist can tie a nice ribbon in their favorite color around the flower arrangement.
Bright colored sunflowers or daises can be uplifting and nice flowers to consider for 'get well' flower gifts. There are also lots of other bright, colorful and cheerful flowers around so it is a good idea to check with your florist as to what flowers are in season if you do not already have a specific flower in mind. If you do have a certain flower in mind that you think will be the perfect 'get well' flower gift, however it is not in season, ask your florist if they can recommend something that is close to it in color, texture and/or scent (depending on why you wanted that specific flower).
If you are thinking of sending a 'get well' flower basket you may be able to 'expand' the flower gift to include maybe some cookies or fruit. If your florist do not provide this service you may ask them if they can save some room in the basket for these items and you can arrange for them (if you are picking the flowers up and delivering them yourself).
When making arrangements to send 'sympathy' flowers to a funeral for example there are different arrangements to consider. Your florist will be able to give you advice as to types of flowers, colors etc. but it may also be a good idea to check with the family as to what they have already arranged for and if there are specific colors or flowers they would like.
First off, if you are sending or buying flowers for someone who is in the hospital, check before hand to make sure flowers are allowed. In some departments, wards and/or institutions flowers may not be allowed due to the risk of allergies.
Some things you may want to consider if flowers are allowed at the hospital are for example that some rooms do not get very much direct sunlight so you may want to choose a flower that is resilient and easy to care for. Ask your florist for some recommendations. Also, few hospitals are able to provide a vase so it is a nice thought to include a vase with your flowers so that the patient can more easily also bring the flower arrangement home. An additional option to a vase is to get a basket of flowers.
In addition to selecting flowers that are appropriate at a hospital you may also want to be sure that you are selecting the right florist. Some florists will offer better service than others and be able to help you send get well flowers to friends and family.