I know it is not orthodox GTD thinking, but I find a Today list to be really invaluable. Each morning I go through all of my next action lists and add between 3 - 5 things to my Today list. I think this is helpful in two ways, 1) it reminds me to review all of my next actions each morning and 2) I feel like I've always completed the most important tasks for the day. It is now 12:45 PM and I've checked off the 5 items on my Today list. I feel like I've done the most important tasks for today, plus I have another 10 hours to tackle other items on my next action lists or just goof off the rest of the day because I have already done what is important.