As I remember, and I remember less and less each day, you can reach higher notes when you are standing.

I certainly appreciate the age/memory humor, Roger, but the reason I'm posting is to point out that one's vocal range can be every bit as constricted at the lower end of one's range as in the upper register. I think this is true for everyone, whether bass or soprano or anywhere in between, even though many of (especially males) are more conscious of the inability to hit high notes, while taking for granted to ability to sing the deeper/lower tones.

Standing helps at both ends of the pitch spectrum, I believe. Also ~ if this is not "thread drift" ~ it's probably at least equally important to be comfortable, psychologically as well as physically, if you want to maximize your range. I find that when I'm unsure of the tune, or nervous for any other reason, it's harder for me to reach low notes that I normally can sing, perhaps even moreso than to sing up into the upper part of my normal range.