It doesn't matter for milliwatt-level receiver testing, but those "2W" attenuators will probably burn out at 2W, and get uncomfortably hot at 1W. This isn't a problem as long as you know about it.
You use attenuators for several purposes, including (as you know) to reduce the power input to delicate test equipment such as the SA. But even at low power levels attenuators can improve your measurements by reducing impedance mismatch in a controlled manner.
For example, if you are testing a filter, it will probably not present a constant 50 Ohm impedance at the input and output ports (especially outside of the filter design frequency), and so the length of coax cable between the signal source, the filter, and the analyzer will also affect the measured filter behavior. By putting (say) 10 dB attenuators at the filter input and output you can greatly reduce this effect and get a better idea of the actual filter characteristics.
Or, some signal sources do not have a well-controlled output impedance, and so connecting cable length will affect the output amplitude/phase. Putting an attenuator at the source output will again reduce this effect.
So, I recommend adding a few 6, 10, 20 dB attenuators to your kit. Probably a few dummy loads as well, although a 20 dB attenuator can often serve this function.
But please be very suspicious of the specs on any of these aliexpress or Amazon attenuators and dummy loads. In most cases I've found the attenuation and frequency response to be acceptable up to 1 GHz (I generally work in the HF region), but the power ratings are usually wildly exaggerated.