This is a matter of taste, and you'll get as many opinions as people...
I doubt you can indicate the half-life and decay mode for the elements. That's a nuclide property that fits in a table of the nuclides. Some elements have a dozen natural isotopes and 30 known isotopes, most with 2-3 decay modes. At best, you can indicate the decay of the most abundant isotope, but some elements are not natural.
I'd like the isotopes listed by decreasing natural abundance, and maybe by decreasing half-life for the unstable ones.
I suggest that you shade and circle the element boxes with different colours to indicate
solid, liquid, gas, maybe cryogenic gas
stable, radioactive, artificial (which isn't the same)
metal, semi-metal, metalloid, transition element. Be clear if "metal" is for a chemist or a solid physicist.
This saves room.
The density, molar volume and specific heat capacity depend on the allotrope. In some cases, especially graphite, the density is only a theoretical value never encountered. This should at least be hinted somewhere. Molar volume and heat capacity are dropaway candidates for a smaller chart.
The radii are very badly defined. To the very least, hint at this somewhere, and tell which convention you use. Good candidate for dropping away.
Most elements have many possible oxidation numbers, check Wiki for that. You might want to restrict to the most common numbers, especially for a smaller table.
I don't care about who discovered an element when.
The abundance in Earth's crust could be interesting. Or the estimated resource: check at USGS. But not the price, which varies too much - or give just a power of ten or a category.
Energy of first ionization? Electronegativity? Redox potentials aren't associated with just an element, but maybe you could tell (colour?) if the uncombined element exists in natural state.
To the melting and boiling points, which I appreciate, you might add the critical temperature, maybe pressure.
You might check the properties given at webelements.com. In a website, they have more room than on a wall chart. I'd find healthy to pick only the properties associated with the elements, not with their isotopes (spin, magnetic moment, thermal neutron absorption...), and use discretion about the ones associated with the state of the element (modulus, speed of sound, conductivity, atomic radius and so on).