I think i'll echo what others have said here a bit, but there's more than sensor.
- Use a polariser. Blue skies get bluer, greens get livelier, water reflections get less, unless there's cloud or i'm inside (sometimes even if i am), the polariser is glued to the lens. Check out my two examples at the bottom, shot about 3 seconds apart, 7D and 15-85, one with polariser, one without, camera jpg with no PP (handheld, ignore the sloping horizon). Take your shots of the church and beach, and think about how much a cpl will do to them.
- Shoot RAW, and learn to PP. This one took me a while to get used to (i use linux and it took me a while to get DPP working, now I use it and haven't looked back). It takes some time to master, i'm still learning, going back over old shots and making them twice as good just from the new techniques i've learnt since i DPPed them the first time. Just a simple contrast or saturation boost, or even dragging the black-point slider up a bit to deepen all your blacks can make all the difference. Another 2 shots down the bottom for examples, the first is the batch-processed-raw (practically the same as a camera-jpg). The second had less than half an hour of PP and a bit of cropping.
- Looking at your examples you liked, the first two stood out to me for their colours, the yellow in the background of the boy, or the colours of the uniforms. The light on both of their faces is also very nice. The examples of yours don't have the colour range, but the portraits have nice face-lighting, a bit of PP could clean them up nicely, especially the one of the girl. PPing portraits to 'pop' is a definite artform, i'm struggling with my latest shots of a mate's engagement party, it's too easy to over-saturate the faces to look like cartoons. But with practice, i'll get there...
- The only differences between FF and crop, is the 'apparent depth of field' you get. Shooting a 50mm f/1.2L wide open from a certain distance on a crop-body, you'll get the exact-same look from a FF sensor in the exact same spot using an 80mm f/1.8. Or shooting with 85mm f/1.2 on a crop, you need a (roughly) 135mm f/1.9 on a 5D for the same shot.
In the first example, the 5D can get shallower DOF because it can go wider to f/1.2 (ok, but at 85mm, not 80).
In the second example, you'll get (practically) exactly the same results using a 7D+85/1.2 as you would with a 5D+135/2.0.
But going the other way, if you mount an EF 85 f/1.2L on a FF sensor, you'd need a 53mm f/0.7 lens on a 7D to get the same shot. Such a lens does not exist (although a 50mm f/0.75 does, but sell your house first). If you 'need' to get your DOF this shallow to make the photo 'pop', you 'need' a FF sensor, it can't be done on a crop. (alternatively, buy a Medium Format body and a 135 f/1.9 lens, don't think they're common and definitely not cheap either).
Same with the 50mm f/1.2L on a 5D. If the photo looks good only at f/1.2, then trying to get the same photo using a 7D you'd need a 31mm f/0.7, again, that lens doesn't exist so you can't get that shot on a 7D.
Once you stop-down past f/4 for more DOF though, it doesn't matter what lens/body you're using, because an equivalent length/aperture exists for a different sensor.
