@Houseman: No, sorry, I may not have been completely clear -- please start with measuring the full span, i.e. select "Span" -> "Full Span". This should select, depending on the specific model of the SSA you're using, a frequency range of 0 to 2.1 or 3.2GHz. If the Resolution Bandwidth setting is set to auomatic, the scan time shouldn't be overly long. If the scan is too slow, change the VBW to automatic or a higher, fixed setting.
Now you should be able to identify the peak that's overloading your SSA and adjust the input attenuation accordingly to eliminate the warning (a margin of at least 10dB should be kept, when you need high spur rejection, even 20dB may be necessary). Then "magnify" the span to the range that's of interest to you and adjust the other parameters accordingly (RBW, VBW if required). You may "play" with the attenuator setting to identify possible intermodulation spurs (if there are, they should vary with the attenuation, otherwise, only the noise background will shift up/down) and find the best setting to conduct your measurement.