There are people who love words that end with an "eee" sound like serendipity, flucidity, and conviviality, but there's something a little too cutesy about them for me. They sound like they came right out a of a romance novel that sports especially flowery cover art.
Some words just make your face feel nice like moist and boisterous. That "oi" sound puckers up your lips like a kiss. Speaking of kisses, saying prunes makes you look like you're blowing a kiss and mouthing the word colorful to someone looks like you're saying, "I love you!"
And if it's a pleasing pout you're looking for instead of a pucker, try capsule, nodule, or podule.....anything ending in "ule". It seems the "u" sound gives the face a good workout in any form. Ukulele, uvula, and universe do the trick, too.
Plant names are my favorites. I love to get a chance to say sultana and clematis. How wonderful is penstemon? Or digitalis? Syringa and Hydrangea get back to the "ng" sounds, but verbena, verbascum, and veronica are like a little party in your mouth.