The Moon ⧃ A ridiculous amount of detail, with features as small as a mile visible. We could go and write paragraphs about how great the views of the Moon are with the 6SE - or arguably any decent telescope - but we couldn’t possibly do it justice, so we’ll let the views speak for themselves.
Mars ⧃ The ice caps are fairly obvious even when Mars is far from Earth. Around opposition you can see a bunch of dark shaded areas, which are just duller colored sand.
Jupiter ⧃ The cloud bands and Great Red Spot look great. With good seeing you can pick out mottled details and ripples within the cloud bands and the brownish polar zones. Jupiter’s 4 large moons are especially obvious as disks when they eclipse and transit the planet.
Saturn ⧃ Saturn’s rings are easily visible as is the Cassini Division in them, the latter provided you have good seeing. Around half a dozen moons can be spotted along with faint variations in the tones of Saturn’s cloud bands. Saturn’s largest moon, Titan, is visibly not a star and appears a slightly gold color.
Uranus ⧃ A small turquoise dot. The moons are out of reach of anything under 10 inches in aperture.
Neptune ⧃ A near-stellar blue dot. Its largest moon Triton can just barely be glimpsed under dark and steady skies.