This is a fairly dicey area, getting clean power for electronics when running from a genset. Take just one area, PC type computers. A lot depends on the quality of the power supply design in the PC. Some have good 'holdup time' and will withstand a brief voltage sag, others will let that computer reboot if you lose power for many milliseconds at all.
The best UPS devices are the
online type. These are expensive. Yep, you get what you pay for. They 'synthesize' their own 120VAC 60Hz waveform from the dirty mains power. There is no direct through power connection.
Falcon Electric is an example of an online UPS supplier.
Then there are the cheaper
offline UPS that most of us are used to. You can get one of those in most any computer store for under a hundred bucks to power an average computer setup. But they are passing through a lot of dirty mains power most of the time they because they are not triggered on until line voltage drops out.
The cheapie UPS types would benefit from some filtering on their outputs if you want to power electronics. No, a 'surge strip' is not really adequate. It only clips very high transient voltage spikes, and not too well at that. And it doesn't mitigate voltage sags at all. There are much better, purpose built filters to correct this, such as the Islatrol Plus units made by Control Concepts. Here's an example of one from an
Ebay auction. These are great filters and trade for around 25-50 dollars used. Plenty of them on Ebay usually. Heres a
more durable link, scroll down to "Islatrol Plus" for a photo and brief description. One other measure, nearly as good, is to get hold of an old, surplus 'constant voltage transformer' like those made by Sola Electric. I have a couple of them here, rated 500VA and 100VA or so. They are nearly as good, especially the 'harmonic neutralized' types. Both of these basic filter types will 'eat' voltage spikes and dips. A 'surge strip' does a very lousy job, by comparison. You don't want 'spike clippers', you want 'line conditioning' filters. I almost think that the constant voltage transformers might be slightly better with a genset if that generator has poor output voltage regulation. The Islatrols can't correct for too high or low a supply voltage, they only clean up transients, but they are better at doing that.
I agree, run your sensitive electronics from a UPS after the genset output, but if you use a cheap UPS you really must have a quality line conditioning filter after that. This is even true under normal home conditions: Dirty mains voltage + voltage sags - no line conditioning = frequent reboots.