I think that space design is important to keep the members not only focused, but also give a sense of a sheltered place, one where ideas are welcome and you can 'just be yourself.' Groove space design is a specialized niche similar to web design, where a strong knowledge of the platform can make a huge difference in effective space design.
Some of the things I do.
* Use the Welcome Tool as a launching pad. I actually prefer PinBoard in many ways for this but it falls into the category below. The much aligned Welcome Tool actually does a decent job, especially if the space creator puts an image there, a good descriptive statement, and includes hot links for navigation to key tools. For quasi-public spaces I also like to include 'community use rules' so that folks know they are free to post items, but to keep things civil.
*Avoid 3rd Party tools until your membership has reached sufficient critical mass for the intent of the space. 3rd Party tools require more downloads and can actually scare off new Groove users.
*Renaming of the tools to fit the context better. Important (and powerful imho) step. Instead of Web Links I will sometimes rename the web tool to "Net Research". Mindmanager is usually renamed anything but Mindmanager (brainstorms, or other things).
*Use the Custom Tool to add a second, third and so on layer of tools. You have to remember that not everybody has a 19" monitor or monitor settings the same as yours. Reduction of clutter.
*Archiving of chats into the Discussion tool. This allows folks to catch up on text chats even if they weren't involved. I will often copy a link to that thread entry after deleting the transcript and place it in the chat window. Clears up clutter, and provides a placemark of the conclusion of a conversation. If you have ever went into a Groove space where there is already old chat text in there you are probably like me and not wanting to disturb the stuff there. And if it isn't your space, you feel sheepish cleaning up the chat to fit your vision of how a space should be. The link to a closed out conversation saves members from this dilemma.