Is #1 and/or #6 Coach? I have similar - see recent WiW's. Mine is small, a cross-body style, which is what I wanted (small enough to tuck in carry on for traveling). It's so difficult for me to advise here since I don't know what size you are looking at, but if it's the same Coach bag, I love it to pieces BUT it definitely won't fit a diaper and yeah, you have to fumble with the flap. Really, mine fits about the same (no more) than a clutch. I love it anyway.
For spring/summer, my requirements are different. I know from experience I want:
1. Something big. For me it's not to carry diapers, but to carry a cardigan and/or scarf and/or rain hat and sunnies and all of that.
2. Something slouchy. Bigger I go, the more slouchy I need, to pull it off, since I'm petite/YMMV. But also, the warmer months just seem to beg for something less tailored and more slouchy. I google "hobo" style constantly but these are slim pickings lately.
3. Something in a light color; my usual is optic white, but the colors you show here I would totally do too! This season I am thinking I'll try something different and go with blush. And Coach has a beautiful blush hobo-ish shoulder bag that has been calling my name lately....
4. If you want something more tailored AND light in color, then trust me on this... you want it to have FEET. Because if you set it down anywhere (which is inevitable), those little feet will keep it looking clean.
That's my personal wish list. I am also on the hunt. Of the bags you show here, #4 and #6 would be of interest to me if in blush. #2 is great but I prefer a zipper. #3 is just like my black Coach and if they are same size, it's going to be too small, trust me, though maybe that style comes in a larger version? It is stiff though. I do love that, but not for summer and fumbling etc.
I've rambled like I am apt to do when I'm exhausted. I hope whatever I've rambled on about, helps! Will be following closely to see what you decide.