My favourite for sleepers in the UK has been Onesies & all in one sleepsuits by the all in one company but just found out that Next are now doing them in their kids range!
And not just talking little kids, this is up to age 16 size, so suitable for teens and any adults of a typical British 16 year old height and build (so suits me fine as most are bigger than me!).
Not footed, but a range of fleece and jersey all-in-one sleepers and from a mainstream store in the UK is rare thing for older kids sizes.
Seems sleepers have become more cool or fun and accepted.