I had one road bike that was hard riding on the front till I switched from the old Continental Ultra Sports to a Vittoria Rubino Pro. Before making the switch in tires, I'd wrapped foam pipe insulation on the bars. Quite comfy, looks like crap. <grin>

I've found that better tires in the upper price ranges that have less rolling resistance are just naturally more comfy riding tires. Of course the wider the tire, the better the ride too, if your bike can handle it.

I'd be skeptical of suspension stems, but who knows? Maybe users of them will chime in.

Depending on how long and what your goals are for riding, I might would keep that fat tire bike as an option. Or........ and many probably think I joking when I say this, but a beach cruiser type bike. Those for short rides are real comfy, IMO.