I would advise reading up on failure -- there's absolutely no need to go to failure with much regularity. It's most likely counterproductive to do so. You'd be better off using a weight that you know you'll get with minimal struggle on free bench, then gradually adding 5 pounds per week until it gets tough. Then grab a spotter when you aren't 100% sure you'll get it and tell him not to touch the bar unless you yell 'spot'. You will add some serious pounds to your bench this way, and will see some nice gains as long as your eating is adequate to allow for growth
Avoid the smith if at all possible. Personally I would do weighted dips and standing overhead presses if you absolutely do not want to bench without the smith.