The only part of LXDE I've used is LXpanel; it's fine but fairly basic. The main reason I use it is because it can be used independently of its desktop environment (I use it with Fvwm just for the systray and menu). Unfortunately for you, in order to customize the menu in LXpanel, you have to edit the config file for the panel; there isn't a GUI for it.
I guess the first question of which desktop environment would suit you is: what features do you want? Obviously you want something zippier than GNOME, which means that KDE is out. I'm kind of surprised that you found XFCE4 (what Xubuntu uses) to be so frustrating; I rather like it. But then I don't tend to edit menus, I just go with the default.
Because of this, I can't speak to how easy or difficult menu-editing is with various DEs, but there are a couple of other lightweight DEs you might want to try out also: Enlightenment, and Fvwm-crystal. (Not Fvwm; it requires a lot of file-editing to customize, which wouldn't suit you. Me, I love it just because it is supremely flexible, but I like getting under the hood.)
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I guess the first question of which desktop environment would suit you is: what features do you want? Obviously you want something zippier than GNOME, which means that KDE is out. I'm kind of surprised that you found XFCE4 (what Xubuntu uses) to be so frustrating; I rather like it. But then I don't tend to edit menus, I just go with the default.
Because of this, I can't speak to how easy or difficult menu-editing is with various DEs, but there are a couple of other lightweight DEs you might want to try out also: Enlightenment, and Fvwm-crystal. (Not Fvwm; it requires a lot of file-editing to customize, which wouldn't suit you. Me, I love it just because it is supremely flexible, but I like getting under the hood.)