I've always found Yuuguu workable. Some years ago, set up up b/c it was cross-platform between Macs and PCs and I, as tech adviser/help desk for the 'rents and others, found it workable to view screens and control computers remotely to help fix problems (e.g. "The internet disappeared" = Firefox icon accidentally deleted). Thankfully, the tech questions are becoming fewer and far between so it's been a few months since I've had to use it.