How can I change my style? When listening to the greats play... I get so jealous!?

When in doubt ,go with the basics and the basic way to improvise and stay near the tonic is to improvise rhythmically on the melody. Take a melody like Misty , which has lots of long notes that allow experimentation and can be improvised on without worrying much as to the harmonic density. Of course improvising this way is not the most wild and deep Jazz of say, Coltrane or Miles Davis working over the chords of a song,but the basics always lead to greater heights. Listen to Stan Getz and the way he plays The girl From Ipanema . He sticks close to the melody and creates the illusion of improvising!