I recently created a game for children that, among other things, requires the knowledge of positive words. So if you need positive words that start with S and don't want to waste your time searching the internet, here is the list!
Superb
Sensational
Sparkling
Strong
Supportive
Sacred
Splendid
Stunning
Successful
Sympathetic
Satisfying
Serene
Special
Spectacular
Spiritual
Stable
Sensitive
Sincere
Soothing
Smooth
Steadfast
Sturdy
Smiling
Sparky
Sassy
Sweet
Savorous
Savvy
Splendid
Supreme