Cheerful and happy:
* Merry
* Joyful
* Cheerful
* Happy
* Glad
* Bright
* Delighted
* Ebullient
* Jubilant
Playful and lighthearted:
* Jocular
* Whimsical
* Spry
* Lively
* Boisterous
* Festive
Informal and friendly:
* Chummy
* Friendly
* Good-natured
* Hearty
* Pleasant
* Genial
Other synonyms:
* Buoyant
* Exuberant
* Merrymaking
* Blithe
* Jovial
The best synonym for "jolly" will depend on the context in which you are using it.