There is a mitzva for everyone to enjoy Ḥol Ha-mo’ed with their family and household members, as we read (Devarim 16:14): “You shall rejoice in your festival with your son and daughter, your male and female slave, the Levite, the stranger, the orphan, and the widow in your communities” (MT, Laws of Yom Tov 6:17).
This mitzva of simḥa should be expressed through food and clothing, as these are the means generally used to express joy. Additionally, since Ḥol Ha-mo’ed is a sacred occasion in a certain sense (see section 1 above), one should sanctify it with “food, drink, and clean clothing” (Sifra, Emor 12:4).
Therefore, it is a mitzva to have two proper meals on each day of Ḥol Ha-mo’ed and to serve bread as well as food that people enjoy. It is also a mitzva to drink a revi’it (roughly 2.5 oz or 75 ml) of wine, which brings joy. The mitzva can be fulfilled with other alcoholic beverages, but wine is the best, as it is the finest beverage. One who enjoys eating meat should preferably eat meat or poultry during these meals. All who honor and glorify the festivals, spending generously to enjoy them with food and drink for the sake of heaven, will receive double reward (Arizal). One who finds it difficult to eat two meat meals a day may skip the meat at one of the meals but should make sure to have other food he enjoys. It is customary to cover the table with a tablecloth throughout Ḥol Ha-mo’ed, as one does on Yom Tov (AHS 530:4).
Since the days of Ḥol Ha-mo’ed are not actually Yom Tov, having a meal with bread then is a mitzva but not an obligation. One who does not want to eat bread during these meals is not required to do so. Similarly, one who does not want to have extra food or to drink wine is not required to do so. Nevertheless, his meals on Ḥol Ha-mo’ed still must be superior to his weekday meals. If he eats the same way on Ḥol Ha-mo’ed as he does during the week, he is denigrating the festival, and the Sages have stated: “One who belittles Ḥol Ha-mo’ed has no portion in the World to Come” (Pirkei Avot 3:11, following Rashi and R. Ovadia of Bertinoro).
Since there is no obligation to eat bread at the Ḥol Ha-mo’ed meals, one who ate bread but forgot to include Ya’aleh Ve-yavo in Birkat Ha-mazon need not repeat it. The basic principle is that a day on which there is no obligation to eat bread, one who forgets to invoke the day need not repeat Birkat Ha-mazon (SA 188:7; 2:6 above).
On Ḥol Ha-mo’ed, there is a mitzva to wear nice clothing that brings one joy. Especially meticulous people wear Shabbat clothes on Ḥol Ha-mo’ed, but this is not obligatory. However, it is obligatory that there be a noticeable difference between the clothes worn on Ḥol Ha-mo’ed and those worn during the week.
Included in the mitzva of simḥa is doing enjoyable things such as singing, dancing, and tiyulim (outings). Each person should do what makes him happy (1:13 above).