Interlocks are cheap, are 50 state code (assuming installed by a certified electrician), and you don't need a suicide cord. The main reason I went with one is because of liability reasons. Some drunk or kid pulls the suicide cord, starts licking the prongs or stuffs it in their nose, then gets shocked... bam, million dollar negligence judgement with triple damages.
Of course, there is the lineman issue... if one goofs up and backfeeds, the poco will know it. Here in Texas, the local utility has a policy of pulling meters when that happens (and not reconnecting until an inspector comes out to see that a certified electrician installed a transfer switch.)
I personally prefer a transfer switch (auto or manual), but they are expensive, and only allow a limited number of circuits.
At least get an interlock kit, at the minimum.